Self-assembly to function: design, synthesis and broad spectrum antimicrobial properties of short hybrid E-vinylogous lipopeptides - Shankar, S. Shiva; Benke, Sushil N.; Nagendra, Narem; Srivastava, Prabhakar Lal; Thulasiram, Hirekodathakallu V.; Gopi, Hosahudya N. (Journal of Medicinal Chemistry, 2013)
Nonribosomal E-vinylogous gamma-amino acids are widely present in many peptide natural products and have been exploited as inhibitors for serine and cysteine proteases. Here, we are reporting the broad spectrum antimicrobial properties and self-assembled nanostructures of various hybrid lipopeptides composed of 1:1 alternating alpha-and E-vinylogous residues. Analysis of the results revealed that self-assembled nanostructures also play a significant role in the antimicrobial and hemolytic activities. In contrast to the alpha-peptide counterparts, vinylogous hybrid peptides displayed excellent antimicrobial properties against various bacterial and fungal strains. Peptides that adopted nanofiber structures displayed less hemolytic activity, while peptides that adopted nanoneedle structures displayed the highest hemolytic activity.

Sensing behavior of atomically thin-layered MoS2 transistors - Late, Dattatray J.; Huang, Yi-Kai; Liu, Bin; Acharya, Jagaran; Shirodkar, Sharmila N.; Luo, Jiajun; Yan, Aiming; Charles, Daniel; Waghmare, Umesh V.; Dravid, Vinayak P.; Rao, C. N. R. (ACS Nano, 2013)
Most of recent research on layered chalcogenides is understandably focused on single atomic layers. However, it is unclear if single-layer units are the most ideal structures for enhanced gas solid interactions. To probe this issue further, we have prepared large-area MoS2 sheets ranging from single to multiple layers on 300 nm SiO2/Si substrates using the micromechanical exfoliation method. The thickness and layering of the sheets were identified by optical microscope, invoking recently reported specific optical color contrast, and further confirmed by AFM and Raman spectroscopy. The MoS2 transistors with different thicknesses were assessed for gas-sensing performances with exposure to NO2, NH3, and humidity in different conditions such as gate bias and light Irradiation. The results show that, compared to the single-layer counterpart, transistors of few MoS2 layers exhibit excellent sensitivity, recovery, and ability to be manipulated by gate bias and green light. Further, our ab initio DFT calculations on single-layer and bilayer MoS2 show that the charge transfer is the reason for the decrease in resistance in the presence of applied field.

Sequence dependent lipid-mediated effects modulate the dimerization of ErbB2 and its associative mutants - Prasanna, Xavier; Praveen, P. J.; Sengupta, Durba (Physical Chemistry Chemical Physics, 2013)
The association of transmembrane helices is an important event in several biological processes, but the factors governing association, especially the non-specific environmental effects, have still not been elucidated. Here, we use coarse-grain molecular dynamics simulations to study the association of ErbB2 transmembrane helices and three ``oncogenic mutants.'' Self-assembly simulations and the dimerization free-energy profiles confirm an energetically-favorable dimerized state for both the wildtype and the mutants. The dissociation free energy of all three mutants is calculated to be larger than the wildtype peptide. Along with favourable protein-protein interactions, non-specific environmental effects are observed to contribute to the association. In particular, local bilayer thinning along with membrane perturbations are seen around the mutants. The membrane perturbations are reduced upon helix association, suggesting that lipid chain packing is an important driving force for helix dimerization. Our results highlight the importance of both specific as well as non-specific driving forces in the association of transmembrane helices.

Short synthesis of (2S,3S)-3-hydroxypipecolic acid - Chavan, Subhash P.; Harale, Kishor R.; Pawar, Kailash P. (Tetrahedron Letters, 2013)
A convenient synthesis of (2S,3S)-3-hydroxypipecolic acid starting from cheap and abundant L-(+)-tartaric acid has been achieved. The strategy employs selective ester reduction and reductive lactamization as key steps. (C) 2013 Elsevier Ltd. All rights reserved.
Keywords: Reductive lactamization; Selective deprotection; Wittig reaction

Silencing an N-acyltransferase-like involved in lignin biosynthesis in nicotiana attenuata dramatically alters herbivory-induced phenolamide metabolism - Gaquerel, Emmanuel; Kotkar, Hemlata; Onkokesung, Nawaporn; Galis, Ivan; Baldwin, Ian T. (Plos One, 2013)
In a transcriptomic screen of Manduca sexta-induced N-acyltransferases in leaves of Nicotiana attenuata, we identified an N-acyltransferase gene sharing a high similarity with the tobacco lignin-biosynthetic hydroxycinnamoyl-CoA: shikimate/quinate hydroxycinnamoyl transferase (HCT) gene whose expression is controlled by MYB8, a transcription factor that regulates the production of phenylpropanoid polyamine conjugates (phenolamides, PAs). To evaluate the involvement of this HCT-like gene in lignin production as well as the resulting crosstalk with PA metabolism during insect herbivory, we transiently silenced (by VIGs) the expression of this gene and performed non-targeted (UHPLC-ESI/TOF-MS) metabolomics analyses. In agreement with a conserved function of N. attenuata HCT-like in lignin biogenesis, HCT-silenced plants developed weak, soft stems with greatly reduced lignin contents. Metabolic profiling demonstrated large shifts (up to 12% deregulation in total extracted ions in insect-attacked leaves) due to a large diversion of activated coumaric acid units into the production of developmentally and herbivory-induced coumaroyl-containing PAs (N', N `'-dicoumaroylspermidine, N', N `'-coumaroylputrescine, etc) and to minor increases in the most abundant free phenolics (chlorogenic and cryptochlorogenic acids), all without altering the production of well characterized herbivory-responsive caffeoyl-and feruloyl-based putrescine and spermidine PAs. These data are consistent with a strong metabolic tension, exacerbated during herbivory, over the allocation of coumaroyl-CoA units among lignin and unusual coumaroyl-containing PAs, and rule out a role for HCT-LIKE in tuning the herbivory-induced accumulation of other PAs. Additionally, these results are consistent with a role for lignification as an induced anti-herbivore defense.

Silicon-induced general, mild, and efficient one-pot, three-component synthesis of amidoalkyl naphthol libraries - Salama, Tarek A. (Synlett, 2013)
A general mild and efficient protocol for the synthesis of amidoalkyl naphthol libraries was achieved utilizing tetrachlorosilane and zinc chloride in dichloromethane at ambient temperature via a one-pot, three-component condensation of various aldehydes, nitriles (amides), and beta-naphthol.
Keywords: amidoalkyl naphthols; combinatorial synthesis; multicomponent reactions; Ritter reaction; tetrachlorosilane

Simple synthesis of the novel antihistaminic drug olopatadine hydrochloride - Chavan, Subhash P.; Lasonkar, Pradeep B. (Synthesis-Stuttgart, 2013)
A new alternative route for the synthesis of olopatadine is described. The present strategy involves a Lewis acid mediated ring opening of a cyclic ether to introduce 3-(dimethylamino)propylidene group as the side chain.
Keywords: antihistaminic drugs; chelates; Lewis acids; spiro compounds; zinc

Single pot conversion of furfuryl alcohol to levulinic esters and gamma-valerolactone in the presence of sulfonic acid functionalized ILs and metal catalysts - Hengne, Amol M.; Kamble, Sumit B.; Rode, Chandrashekhar V. (Green Chemistry, 2013)
Ionic liquids functionalized with acidic anions, HSO4, ClSO3H, PTSA, TFA (MIm), HSO4 and TFA (NMP) were found to efficiently (99% conversion) catalyze the alcoholysis of furfuryl alcohol (FAL) in the presence of methanol, ethanol, n-butanol and isopropyl alcohol (IPA) to the corresponding levulinic acid esters under mild temperature (90-130 degrees C) conditions. The extended alkyl chain length of [MIm] using 1,4-butane sultone enhanced the Bronsted acidity of [BMIm-SH][HSO4] catalyst resulting into the highest selectivity of >95% to Me-LA. An increase in both temperature and catalyst concentration increased the furfuryl alcohol conversion and selectivity to levulinate esters. In contrast, an increase in the substrate concentration from 5 to 15% caused a decrease in Me-LA selectivity due to accumulation of intermediate ethers of furfuryl alcohol. Using a combination of [BMIm-SH][HSO4] and 5% Ru/C catalyst, direct conversion of FAL to gamma-valerolactone (GVL) is shown for the first time. A complete conversion of FAL with the highest selectivity of 68% to GVL could be achieved under optimum conditions while higher Ru loading enhanced the GVL selectivity to 94% in the hydrogenation step of this tandem approach. Our catalyst system could be efficiently recycled five times retaining the original activity and selectivity levels.

Solution and in silico studies on the recombinant lectin from Cicer arietinum seeds - Wakankar, Madhurima S.; Krishnasastry, Musti V.; Jaokar, Tulika M.; Patel, Krunal A.; Gaikwad, Sushama M. (International Journal of Biological Macromolecules, 2013)
The Cicer arietinum seed lectin was cloned and expressed in Escherichia coli and purified in active form. Conformational characterization of the recombinant lectin (rCAL) was performed using biophysical and bioinformatics tools. Thermal denaturation of rCAL caused rapid secondary structural rearrangements above 50 degrees C and transient exposure of hydrophobic residues at 55 degrees C, leading to aggregation. Treatment of rCAL with GdnHCl resulted in unfolding followed by dissociation of the dimer. The single tryptophan in rCAL present on the surface of the protein is surrounded by hydrophobic and acidic amino acids and exists as different conformers. The experimental observations correlated well with the structural information revealed from the homology model of rCAL. (C) 2013 Elsevier B.V. All rights reserved.
Keywords: Aggregation; BL21-CodonPlus (DE3)-RIL cells; Cicer lectin; Homology model; Steady-state and time resolved fluorescence; Unfolding

Solvent-free, highly efficient one-pot multi-component synthesis of 1-amido- and 1-carbamato-alkyl naphthols/phenols catalyzed by ethylammonium nitrate as reusable ionic liquid under neat reaction condition at ambient temperature - Mulla, Shafeek Abdul Rashid; Salama, Tarek A.; Pathan, Mohsinkhan Y.; Inamdar, Suleman M.; Chavan, Santosh S. (Tetrahedron Letters, 2013)
A solvent-free, environmentally clean, mild, and simple one-pot multi-component protocol has been developed for the efficient synthesis of 1-amido- and 1-carbamato-alkyl naphthols/phenols in excellent yields via one-pot three-component condensation of various aldehydes, amides/carbamates/urea, and naphthols/phenols using ethylammonium nitrate (EAN) as a reusable ionic liquid catalyst under neat reaction condition at ambient temperature. (c) 2012 Elsevier Ltd. All rights reserved.
Keywords: Aldehyde; amide; Carbamate Phenol; Ethylammonium nitrate (EAN); Urea

Solvent-induced self-assembly of hydrogen bonded P4VP-perylenebisimide comb polymer - Narayan, Rekha; Asha, S. K. (Journal of Materials Chemistry C, 2013)
Polymeric supramolecular assemblies were formed when an unsymmetric perylenebisimide substituted with ethylhexyl chains on one end and functionalized with 3-pentadecylphenol at the other termini (PDP-UPBI) was complexed with poly(4-vinylpyridine) (P4VP) via hydrogen-bonding interaction. The self-assembly behavior of this polymeric supramolecule poly(4-vinylpyridine)-perylenebisimide P4VP(PDP-UPBI)(1.0) was studied in solvents of varying polarity like chloroform (CHCl3) and methylcyclohexane (MCH). Variable concentration and variable temperature proton NMR studies in CDCl3 and deuterated 1,1,2,2-tetrachloroethane (TCE), respectively, revealed the polymeric nature of the perylenebisimide upon complexation and the high thermal stability of the self organized structures in solution. The improved solubility afforded by the complexation enabled variable temperature UV-Vis absorption studies in the non-polar solvent MCH, which indicated the existence of strong face-to-face stacked H-type aggregates. The strong fluorescence quenching in MCH also supported the identification of the nature of aggregates as co-facial H-type. Although the existence of aggregates was not very evident in dilute solutions of chloroform, the fluorescence of the P4VP(PDP-UPBI) 1.0 was quenched compared to that of PDP-UPBI. Thin spin coated films of the complex from chloroform exhibited features of rotationally displaced H-type aggregates characterized by blue shift of absorption maxima and the appearance of a new red shifted peak at 540 nm with weak aggregate emission beyond 600 nm. Morphology analysis of drop cast samples using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the formation of micrometer long multilamellar nanofibers from CHCl3 and two dimensional multilamellar nanosheets upon switching the solvent to MCH.

Solving the problem of negative populations in approximate accelerated stochastic simulations using the representative reaction approach - Kadam, Shantanu; Vanka, Kumar (Journal of Computational Chemistry, 2013)
Methods based on the stochastic formulation of chemical kinetics have the potential to accurately reproduce the dynamical behavior of various biochemical systems of interest. However, the computational expense makes them impractical for the study of real systems. Attempts to render these methods practical have led to the development of accelerated methods, where the reaction numbers are modeled by Poisson random numbers. However, for certain systems, such methods give rise to physically unrealistic negative numbers for species populations. The methods which make use of binomial variables, in place of Poisson random numbers, have since become popular, and have been partially successful in addressing this problem. In this manuscript, the development of two new computational methods, based on the representative reaction approach (RRA), has been discussed. The new methods endeavor to solve the problem of negative numbers, by making use of tools like the stochastic simulation algorithm and the binomial method, in conjunction with the RRA. It is found that these newly developed methods perform better than other binomial methods used for stochastic simulations, in resolving the problem of negative populations. (C) 2012 Wiley Periodicals, Inc.
Keywords: approximate methods; binomial distributions; Gillespie algorithm; Kinetic Monte Carlo; Poisson distributions; representative reaction approach; Stochastic simulations

Spatial and temporal changes in the volatile profile of alphonso mango upon exogenous ethylene treatment - Chidley, Hemangi G.; Kulkarni, Ram S.; Pujari, Keshav H.; Giri, Ashok P.; Gupta, Vidya S. (Food Chemistry, 2013)
Alphonso is a highly favoured and exported mango cultivar among the vast mango germplasm of India. Being a climacteric fruit, ethylene plays an important role in ripening of mango. For deeper understanding of effect of pre-climacteric ethylene treatment on volatile profiles of Alphonso mango, 26 volatiles were tracked through six ripening stages of pulp and skin of ethylene-treated and control Alphonso fruits. The study revealed accelerated ripening in terms of early appearance of ripening-specific compounds, lactones and mesifuran, upon ethylene treatment. While the level of lactones remained unaffected, the mesifuran level vastly increased upon ethylene treatment. Skin showed high terpene content while pulp had higher amount of lactones compared to skin. This work points towards involvement of ethylene as a natural hormone in the biosynthesis of lactones and furanones in naturally ripened fruits; whereas, an increase in the terpene level during ripening appears to be independent of ethylene. (C) 2012 Elsevier Ltd. All rights reserved.
Keywords: Ethylene; Flavour; Mango; Pre-climacteric; Ripening; Volatiles

Spin transport and magnetic correlation parameters for graphene-like nanocarbon sheets doped with nitrogen - Alegaonkar, Ashwini P.; Kumar, Arvind; Patil, Sagar H.; Patil, Kashinath R.; Pardeshi, Satish K.; Alegaonkar, Prashant S. (Journal of Physical Chemistry C, 2013)
Globally, graphene magnetism has captivated the attention of researchers in recent years. To obtain magnetic ordering, irregularities in the carbon network, like defects, adatoms, etc., are essential. Herein, we report on spin transport and magnetic correlations in graphene-like nanocarbon sheets (GNCs) that were doped with nitrogen by use of tetrakis(dimethylamino)ethylene (TDAE). The spin transport measurements, performed by electron spin resonance technique, showed that both spin-spin and spin-lattice relaxation times are increased by nitrogen doping. The magnetic correlations, measured on a vibrating sample magnetometer, showed that ordering parameters are reduced for nitrogen-loaded GNCs. Chemical analysis, carried out via electron spectroscopy, revealed that nitrogen atoms exchange couples electron-to-hole with the carbon network Analysis of I-V measurements showed that higher-order resistance is appreciably decreased for nitrogen-doped GNCs. The observed decrease is due to an increase in nonbonding states baying small local density. After doping, states in this region may be localized pi spin populated around the doped region. By and large, the approximately 20% magnetization that exists in GNCs is found to be reduced to 5% by introduction of nitrogen.

Stabilization of graphene quantum dots (GQDs) by encapsulation inside zeolitic imidazolate framework nanocrystals for photoluminescence tuning - Biswal, Bishnu P.; Shinde, Dhanraj B.; Pillai, Vijayamohanan K.; Banerjee, Rahul (Nanoscale, 2013)
Luminescent graphene quantum dots (GQDs) are encapsulated and stabilized in Zeolitic Imidazolate Framework (ZIF-8) nanocrystals. The GQDs are well confined due to the adsorption on the growing face of the ZIF-8 nanocrystals and have a profound effect on the shape of the nanocrystals from rhombic dodecahedron to spherical. Stabilizing GQDs inside the ZIF-8 nanocrystals results in tailoring of the photoluminescence emission (ca. 32 nm, bathochromic shift) of the GQD@ZIF-8 nanocrystal composite even after 3 months of aging under normal laboratory conditions. Also the water adsorption (at STP) capacity increased for the GQD@ ZIF-8 composite as compared to the pristine ZIF-8.

Static and dynamic magnetic properties and effect of surface chemistry on the morphology and crystallinity of DyCrO3 nanoplatelets - Gupta, Preeti; Bhargava, Richa; Das, Raja; Poddar, Pankaj (RSC Advances, 2013)
In this contribution, the structural and magnetic properties of DyCrO3 nanoplatelets, synthesized by a hydrolytic sol-gel method, have been investigated. The crystalline phase of DyCrO3 was attained at the decomposition temperature of 800 degrees C for citric acid and oxalic acid, respectively and their structural analysis indicates a distorted orthorhombic perovskite structure of the DyCrO3 nanoplatelets. The dc-magnetization curve shows the Neel temperature of similar to 144 and similar to 146 K for DyCrO3 nanoplatelets synthesized using citric acid (DCO (C)) and oxalic acid (DCO (O)), respectively. In addition, DCO (O) shows weak anomalies at similar to 22 and similar to 6 K in the zero-field-cooled and field-cooled magnetization curves. Below the Neel temperature, DCO (C) and DCO (O) exhibit cross-over from positive to negative magnetization at similar to 143 and similar to 145 K, respectively. This was attributed to a Dy3+-Cr3+ interaction, which resulted in a weak ferromagnetic coupling (seen as a small opening in the M-H curves). The low temperature transition observed at similar to 6 K can be assigned to the onset of Dy3+-Dy3+ antiferromagnetic interaction.

Static and dynamic magnetic properties and interplay of Dy3+, Gd3+ and Mn3+ spins in orthorhombic DyMnO3 and GdMnO3 nanoparticles - Das, Raja; Jaiswal, Adhish; Poddar, Pankaj (Journal of Physics D-Applied Physics, 2013)
Single-phase orthorhombic DyMnO3 and GdMnO3 nanoparticles in the size range 60-70 and 35-45 nm, respectively, were synthesized using a modified hydrothermal method. The magnetic property measurements of DyMnO3 nanocrystals show anomalies around similar to 43K (antiferromagnetic (AFM) coupling between Mn3+ spins) and at 7K in the form of a peak in the zero-field-cooled curve (AFM coupling between Dy3+ spins). Whereas, GdMnO3 undergoes a phase transition at similar to 42K from paramagnetic to an incommensurate-antiferromagnetic phase (ICAFM) followed by a second anomaly at similar to 22 K, which could be associated with the transition from ICAFM into a canted A-type AFM ordering of the Mn3+ spins. This transition is followed by a long-range ordering of the Gd3+ moments at 6K yielding the canting of the Gd3+ spins with a ferromagnetic (FM) component antiparallel to the FM moment of the canted Mn3+ spins. No anomaly near the Neel temperature of the Mn moments for both DyMnO3 and GdMnO3 nanoparticles was observed in ac magnetization which were observed in dc magnetization. The room temperature Raman spectra of DyMnO3 shows two most intense Raman modes at 480 and 609 cm(-1) which can be assigned to an antisymmetric Jahn-Teller stretching mode and a symmetric or breathing stretching mode, respectively, involving Mn-O bond stretching.

Stepwise metal-ligand cooperation via a reversible aromatization-deconjugation-sequence in ruthenium complexes with a tetradentate phenanthroline-based ligand - Langer, Robert; Fuchs, Ido; Vogt, Matthias; Balaraman, Ekambaram; Diskin-Posner, Yael; Shimon, Linda J. W.; Ben-David, Yehoshoa; Milstein, David (Chemistry - A European Journal, 2013)
The synthesis and reactivity of ruthenium complexes containing the tetradentate phenanthroline-based phosphine ligand 2,9-bis((di-tert-butylphosphino)methyl)-1,10-phenanthroline (PPhenP) is described. The hydrido chloro complex [RuHCl(PPhenP)] (2) undergoes facile dearomatization upon deprotonation of the benzylic position, to give [RuH(PPhenP-H)] (4). Addition of dihydrogen to 4 causes rearomatization of the phenanthroline moiety to trans-[Ru(H)2(PPhenP)] (5), followed by hydrogenation of an aromatic heterocycle in the ligand backbone, to give a new dearomatized and deconjugated complex [RuH(PPhenP*-H)] (6). These aromatization/deconjugation steps of the coordinated ligand were demonstrated to be reversible and operative in the dehydrogenation of primary alcohols without the need for a hydrogen acceptor. This aromatization/deconjugation sequence constitutes an unprecedented mode of a stepwise cooperation between the metal center and the coordinated ligand.

Structural and catalytic properties of a novel vanadium containing solid core mesoporous silica shell catalysts for gas phase oxidation reaction - Venkatathri, N.; Pillai, Vijayamohanan K.; Rajini, A.; Raju, M. Nooka; Reddy, I. A. K. (Journal of Chemical Sciences, 2013)
A novel vanadium containing solid core mesoporous silica shell catalyst was synthesized with different Si/V ratios by sol-gel method under neutral conditions. The synthesized materials were characterized by various techniques and gas phase diphenyl methane oxidation reaction. The mesoporosity combined with microporosity are formed by incorporation of octadecyltrichloro silane and triethylamine in the catalyst and it was found out from E-DAX and BET-surface area analysis. The material was found to be nanocrystalline. Vanadium is present as V4 + species in as-synthesized samples and convert to V5 + on calcination. Most of the vanadium is present in tetrahedral or square pyramidal environment. Incorporation of vanadium in silica framework was confirmed by Si-29 MAS NMR analysis. Among the various vanadium containing solid core mesoporous silica shell catalysts, the Si/V = 100 ratio exhibited maximum efficiency towards diphenyl methane to benzophenone gas phase reaction. The optimum condition required for maximum conversion and selectivity was found out from the catalytic studies.
Keywords: diphenylmethane; Gas phase oxidation; vanadium containing solid core mesoporous silica shell

Structural and dynamical properties of polyethylenimine in explicit water at different protonation states: a molecular dynamics study - Choudhury, Chandan Kumar; Roy, Sudip (Soft Matter, 2013)
PEI is a pH sensitive polymer which acts as a proton sponge in acidic conditions. Despite many experimental and theoretical efforts, a fundamental understanding of the structure and dynamics of linear PEI chains on the atomistic level at different protonation states in dilute solutions remains a topic of discussion. This report analyses the structural properties of PEI at different protonation states, which are representative of different pH, using all atomistic molecular dynamic simulations. The structural properties revealed that the polymer at high pH (basic medium) is highly coiled, while at low pH (strong acidic conditions) the chains are elongated. We studied the dynamics and ordering of water molecules that are part of the solvation shells of the PEI chains at different protonation states. We observe that the water molecules are ordered along the polymer backbone for a completely protonated PEI chain (i.e. in the case of acidic pH) and hop to the neighbouring solvation shell. The residence time and the self-diffusion of water molecules in the solvation shells and their activation barriers were also calculated and analysed further. We concluded the study by correlating the solvation shell water dynamics and the structure of the PEI chain at different protonation states.

Structural and logical analysis of a comprehensive hedgehog signaling pathway to identify alternative drug targets for glioma, colon and pancreatic cancer - Chowdhury, Saikat; Pradhan, Rachana N.; Sarkar, Ram Rup (Plos One, 2013)
Hedgehog is an evolutionarily conserved developmental pathway, widely implicated in controlling various cellular responses such as cellular proliferation and stem cell renewal in human and other organisms, through external stimuli. Aberrant activation of this pathway in human adult stem cell line may cause different types of cancers. Hence, targeting this pathway in cancer therapy has become indispensable, but the non availability of detailed molecular interactions, complex regulations by extra- and intra-cellular proteins and cross talks with other pathways pose a serious challenge to get a coherent understanding of this signaling pathway for making therapeutic strategy. This motivated us to perform a computational study of the pathway and to identify probable drug targets. In this work, from available databases and literature, we reconstructed a complete hedgehog pathway which reports the largest number of molecules and interactions to date. Using recently developed computational techniques, we further performed structural and logical analysis of this pathway. In structural analysis, the connectivity and centrality parameters were calculated to identify the important proteins from the network. To capture the regulations of the molecules, we developed a master Boolean model of all the interactions between the proteins and created different cancer scenarios, such as Glioma, Colon and Pancreatic. We performed perturbation analysis on these cancer conditions to identify the important and minimal combinations of proteins that can be used as drug targets. From our study we observed the under expressions of various oncoproteins in Hedgehog pathway while perturbing at a time the combinations of the proteins GLI1, GLI2 and SMO in Glioma; SMO, HFU, ULK3 and RAS in Colon cancer; SMO, HFU, ULK3, RAS and ERK12 in Pancreatic cancer. This reconstructed Hedgehog signaling pathway and the computational analysis for identifying new combinatory drug targets will be useful for future in-vitro and in-vivo analysis to control different cancers.

Structural design of coordination polymers - Du, Miao; Banerjee, Rahul; Shimizu, George K. H. (Crystengcomm, 2013)

Structural isomerism leading to variable proton conductivity in indium(III) isophthalic acid based frameworks - Panda, Tamas; Kundu, Tanay; Banerjee, Rahul (Chemical Communications, 2013)
Proton conductivity has been studied thoroughly in two isomeric In(III)-isophthalate based MOFs. In-IA-2D-1 is capable of showing proton conductivity (3.4 x 10(-3) S cm(-1)) under humidified conditions (98% RH), whereas In-IA-2D-2 can conduct protons (2.6 x 10(-5) S cm(-1)) under humidified as well as anhydrous conditions.

Structural modelling of substrate binding and inhibition in penicillin V acylase from pectobacterium atrosepticum - Avinash, Vellore Sunder; Panigrahi, Priyabrata; Suresh, C. G.; Pundle, Archana V.; Ramasamy, Sureshkumar (Biochemical and Biophysical Research Communications, 2013)
Penicillin V acylases (PVAs) and bile salt hydrolases (BSHs) have considerable sequence and structural similarity; however, they vary significantly in their substrate specificity. We have identified a PVA from a Gram-negative organism, Pectobacterium atrosepticum (PaPVA) that turned out to be a remote homolog of the PVAs and BSHs reported earlier. Even though the active site residues were conserved in PaPVA it showed high specificity towards penV and interestingly the penV acylase activity was inhibited by bile salts. Comparative modelling and docking studies were carried out to understand the structural differences of the binding site that confer this characteristic property. We show that PaPVA exhibits significant differences in structure, which are in contrast to those of known PVAs and such enzymes from Gram-negative bacteria require further investigation. (C) 2013 Elsevier Inc. All rights reserved.
Keywords: Bile salt hydrolase; docking; Homology modelling; Inhibition; Pectobacterium; Penicillin acylase

Structural variations of D-pi-A dyes influence on the photovoltaic performance of dye-sensitized solar cells - Marszalek, Magdalena; Nagane, Satyawan; Ichake, Amol; Humphry-Baker, Robin; Paul, Vincent; Zakeeruddin, Shaik M.; Gratzel, Michael (RSC Advances, 2013)
Two new organic D-pi-A dyes containing identical pi-conjugated spacer and anchoring/acceptor moieties but different donor groups were designed and synthesized. These dyes containing didodecylcyclopentadithiophene (CPDT) as a spacer, cyanoacrylic acid as an acceptor and N-butyl-carbazole or N-butyl-phenothiazine moieties as electron donor groups are labelled as V4 and V11 dyes, respectively. The variation in the donor group of these two dyes, that influences the photophysical, electrochemical and photovoltaic parameters, was investigated. The highest photovoltaic conversion efficiency of 7.5% was obtained with V4 dye at AM 1.5 G full sunlight intensity (100 mWcm(-2)). Comparison of phenothiazine donor dyes with two different pi-conjugated spacers, CPDT (V11) and vinyl thiophene (V7) containing devices shows that the V-oc of V7 dye is lower than that of V11 due to the downward shift of the conduction band edge. Transient photovoltage and electrochemical impedance spectroscopy measurements were performed to explain the differences in the PV parameters by varying the donors and/or spacer groups.

Structural-functional insights of single and multi-domain capsicum annuum protease inhibitors - Mishra, Manasi; Joshi, Rakesh S.; Gaikwad, Sushama M.; Gupta, Vidya S.; Giri, Ashok P. (Biochemical and Biophysical Research Communications, 2013)
Pin-II protease inhibitors (PIs) are the focus of research interest because of their large structural-functional diversity and relevance in plant defense. Two representative Capsicum annuum PI genes (CanPI-15 and -7) comprising one and four inhibitory repeat domains, respectively, were expressed and recombinant proteins were characterized. beta-Sheet and unordered structure was found predominant in CanPI-15 while -7 also displayed the signatures of polyproline fold, as revealed by circular dichroism studies. Inhibition kinetics against bovine typsin indicated three times higher potency of CanPI-7 (K-i similar to 57 mu M) than -15 (similar to 184 mu M). Activity and structural stability of these CanPIs were revealed under various conditions of pH, temperature and denaturing agent. Structure prediction, docking studies with proteases and mass spectroscopy revealed the organization of multiple reactive site loops of multi domain PIs in space as well as the steric hindrances imposed while binding to proteases due to their close proximity. (C) 2012 Elsevier Inc. All rights reserved.
Keywords: CanPI; Circular dichroism; Disulfide bonding; Potato type-II protease inhibitors; Protein stability

Structure elucidation of beta-cyclodextrin-xylazine complex by a combination of quantitative H-1-H-1 ROESY and molecular dynamics studies - Ali, Syed Mashhood; Fatma, Kehkeshan; Dhokale, Snehal A. (Beilstein Journal of Organic Chemistry, 2013)
The complexation of xylazine with beta-cyclodextrin was studied in aqueous medium. H-1 NMR titrations confirmed the formation of a 1:1 inclusion complex. A ROESY spectrum was recorded with long mixing time which contained TOCSY artifacts. It only confirmed the presence of xylazine aromatic ring in the beta-cyclodextrin cavity. No information regarding the mode of penetration, from the wide or narrow side, could be obtained. We calculated the peak intensity ratio from the inter-proton distances for the most stable conformations obtained by molecular dynamics studies in vacuum. The results show that highly accurate structural information can be deduced efficiently by the combined use of quantitative ROESY and molecular dynamics analysis. On the other hand, a ROESY spectrum with no spin diffusion can only compliment an averaged ensemble conformation obtained by molecular dynamics which is generally considered ambiguous.
Keywords: beta-cyclodextrin; inclusion complex; ROESY; simulation studies; xylazine

Structure-property relationship of different types of polyester industrial yarns - Samui, Barun Kumar; Prakasan, Manikanda Priya; Ramesh, C.; Chakrabarty, Debabrata; Mukhopadhyay, R. (Journal of the Textile Institute, 2013)
Four major types of polyester industrial yarns (1000 Denier) which are used commercially were studied for their key structural parameters. An attempt has been made to establish a relationship between morphology and properties of these yarns. High tenacity (HT) polyester yarn has the highest birefringence, amorphous orientation, and long period but is relatively less crystalline. High shrinkage characteristic of HT polyester yarn can be accounted for its higher amorphous orientation. High modulus low shrinkage (HMLS) polyester yarn has higher crystallinity and crystal size compared to HT yarn. Fraction of tie molecules of these yarns has been calculated and found that low shrinkage (LS) and super low shrinkage (SLS) yarns have lesser tie molecules. These LS and SLS yarns are tailor-made to achieve lower shrinkage and at the same time maintaining a good level of tenacity. This is achieved with lower amorphous orientation in the final drawn yarn structure. Amorphous orientation was found to have stronger influence than any other structural parameter on the key yarn properties like modulus, tenacity, elongation, and shrinkage.
Keywords: modulus; orientation; polyester; shrinkage; structure

Studies on fabrication, characterization, and metal extraction using metal chelating nonwoven nanofiber mats of poly(vinyl alcohol) and sodium alginate blends - Rathna, G. V. N.; Birajdar, Mallinath S.; Bhagwani, Manish; Paul, V. L. (Polymer Engineering and Science, 2013)
Poly(vinyl alcohol) and sodium alginate blends with and without the metal chelate, bis(2,4,4-trimethylpentyl)phosphinic acid were prepared in various compositions and fabricated to stable nanofibers and films to evaluate their efficacy for metals adsorption and desorption. Surface morphology of the nanofibers was characterized by scanning electron microscopy. The solution properties and variation in content of sodium alginate in the feed mixture have influenced morphology of nanofibers. However, influence of bis(2,4,4-trimethylpentyl)phosphinic acid was insignificant. The films and nanofibers were characterized using Fourier transform infrared spectroscopy, differential scanning calorimetry, thermo gravimetric analysis, and X-ray diffraction to understand compatibility between polymers, thermal stability, decomposition temperature, and variations in crystallinity. Metal adsorption studies for nanofiber mats comprising bis(2,4,4-trimethylpentyl)phosphinic acid were demonstrated using copper (II), cobalt(II), and nickel(II) salts. The nanofibers adsorbed more copper (363 mg/g) when compared with films (105 mg/g). Nanofiber mats immobilized with bis(2,4,4-trimethylpentyl)phosphinic acid adsorbed copper in greater magnitude (497 mg/g) than nanofiber mats without bis(2,4,4-trimethylpentyl)phosphinic acid (363 mg/g). However, adsorption of cobalt and nickel was very low to be detected. The metal adsorption and desorption studies were also confirmed by energy dispersive X-ray spectroscopy. POLYM. ENG. SCI., 2013. (c) 2012 Society of Plastics Engineers

Study of grafting of polylactic acid and its copolymer with 12-hydroxy stearic acid on the surface of MWCNT by 13CCP/MAS and AFM - Pandey, Asutosh K.; Garnaik, Baijayantimala (International Journal of Research in Pharmacy and Chemistry, 2013)
The purpose of this study to study the structure property relationship of grafted material on MWCNT, the determination of NMR nuclei spin-lattice (T1) and spin-spin (T2) relaxation times suggest that the broaden signals are associated with diamagnetic species namely the nanotube attached polymer moieties. the AFM image of PLA oligomer grafted MWCNTs and topography patterns comprised of height from 0-250 nm and the side lengths ranging from 0.0 to 7.7 µm. Surface patches are formed randomly distributed employing that the presence of side chain hanged at 12-postion in the copolymer grafted on MWCNTs.

Study of hydration of sarcosine, formation of its zwitterion and their different oligomers in aqueous media: a Raman spectroscopic and theoretical study - Sharma, Poornima; Singh, Dheeraj K.; Gupta, Vineet; Asthana, B. P.; Mishra, P. C.; Singh, Ranjan K. (Spectrochimica Acta Part A-Molecular and Biomolecular Spectroscopy, 2013)
{Raman spectra of the biologically important molecule sarcosine (SAR) (C3H7NO2) were studied experimentally in aqueous solution at different concentrations. These spectra were also calculated theoretically using density functional theory (DFT) at the B3LYP/6-31 1++G(d,p) level. Further, all the observed normal modes were assigned through potential energy distribution (PED). Geometry optimization of SAR produced its three conformers with slightly different energies. The lowest energy conformer of SAR was selected for a systematic solvation study wherein different numbers of water molecules (nW
Keywords: DFT calculations; Hydration; Oligomer; Raman spectra; Sarcosine; Zwitterion

Study of interatomic coulombic decay of Ne(H2O)(n) (n=1,3) clusters using equation-of-motion coupled-cluster method - Ghosh, Aryya; Pal, Sourav; Vaval, Nayana (Journal of Chemical Physics, 2013)
Interatomic Coulombic decay (ICD) is an efficient and ultrafast radiationless decay mechanism which can be initiated by removal of an electron from the inner-valence shell of an atom or molecule. Generally, the ICD mechanism is prevailed in weakly bound clusters. A very promising approach, known as CAP/EOM-CC, consists of the combination of complex absorbing potential (CAP) with the equation-of-motion coupled-cluster (EOM-CC) method, is applied for the first time to study the nature of the ICD mechanism. We have applied this technique to determine the lifetime of an auto-ionized, inner-valence excited state of the NeH2O, Ne(H2O)(2), and Ne(H2O)(3) systems. The lifetime is found to be very short and decreases significantly with the number of neighboring water molecules. (C) 2013 AIP Publishing LLC.

Sugar furanoid trans-vicinal diacid as a gamma-turn inducer: synthesis and conformational study - Vangala, Madhuri; Dhokale, Snehal A.; Gawade, Rupesh L.; Pattuparambil, Rajamohanan R.; Puranik, Vedavati G.; Dhavale, Dilip D. (Organic & Biomolecular Chemistry, 2013)
A simple method for the synthesis of a sugar furanoid trans vicinal diacid and its incorporation into the N-terminal tetrapeptide sequence (H-Phe-Trp-Lys-Thr-OH) to get glycopeptide 8 has been described. 2D NMR and MD simulation studies of 8 clearly show that the sugar diacid adopts a gamma-turn conformation towards the N-terminus.

Superior field emission properties of layered WS2-RGO nanocomposites - Rout, Chandra Sekhar; Joshi, Padmashree D.; Kashid, Ranjit V.; Joag, Dilip S.; More, Mahendra A.; Simbeck, Adam J.; Washington, Morris; Nayak, Saroj K.; Late, Dattatray J. (Scientific Reports, 2013)
We report here the field emission studies of a layered WS2-RGO composite at the base pressure of similar to 1 x 10(-8) mbar. The turn on field required to draw a field emission current density of 1 mu A/cm(2) is found to be 3.5, 2.3 and 2 V/mu m for WS2, RGO and the WS2-RGO composite respectively. The enhanced field emission behavior observed for the WS2-RGO nanocomposite is attributed to a high field enhancement factor of 2978, which is associated with the surface protrusions of the single-to-few layer thick sheets of the nanocomposite. The highest current density of similar to 800 mu A/cm(2) is drawn at an applied field of 4.1 V/mu m from a few layers of the WS2-RGO nanocomposite. Furthermore, first-principles density functional calculations suggest that the enhanced field emission may also be due to an overalp of the electronic structures of WS2 and RGO, where graphene-like states are dumped in the region of the WS2 fundamental gap.

Supplementation of medium with diammonium hydrogen phosphate enhanced the D-lactate dehydrogenase levels leading to increased D-lactic acid productivity - Singhvi, Mamata; Jadhav, Akanksha; Gokhale, Digambar V. (Bioresource Technology, 2013)
The production of D-lactic acid by Lactobacillus lactis RM2-24 was investigated using modified media to increase the efficiency of the fermentation process. The results indicated that the addition of 5 g/l peptone and 1 g/l (NH4)(2)HPO4 enhanced D-lactic acid production by 32%, as compared to that obtained from non supplemented media, with a productivity of 3.0 g/l/h. Lactate dehydrogenase (LDH) expression profile in these different media was studied which resulted in appearance of additional LDH isoform produced by cells when they were grown in HSYE supplemented with (NH4)(2)HPO4. The additional LDH appears to be L-LDH contributing to production of L-lactic acid in the fermented broth. This is totally new information in the lactic acid fermentation and could be very useful to industries engaged in D-lactic acid production. (c) 2013 Elsevier Ltd. All rights reserved.
Keywords: D(-) lactic acid production; Lactate dehydrogenase; Lactobacillus delbrueckii Uc-3; Lactobacillus lactis RM2-24

Supramolecular nanoparticles that target phosphoinositide-3-kinase overcome insulin resistance and exert pronounced antitumor efficacy - Kulkarni, Ashish A.; Roy, Bhaskar; Rao, Poornima S.; Wyant, Gregory A.; Mahmoud, Ayaat; Ramachandran, Madhumitha; Sengupta, Poulomi; Goldman, Aaron; Kotamraju, Venkata Ramana; Basu, Sudipta; Mashelkar, Raghunath Anant; Ruoslahti, Erkki; et al. (Cancer Research, 2013)
The centrality of phosphoinositide-3-kinase (PI3K) in cancer etiology is well established, but clinical translation of PI3K inhibitors has been limited by feedback signaling, suboptimal intratumoral concentration, and an insulin resistance ``class effect.'' This study was designed to explore the use of supramolecular nanochemistry for targeting PI3K to enhance antitumor efficacy and potentially overcome these limitations. PI3K inhibitor structures were rationally modified using a cholesterol-based derivative, facilitating supramolecular nanoassembly with L-alpha-phosphatidylcholine and DSPE-PEG [1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polythylen e glycol)]. The supramolecular nanoparticles (SNP) that were assembled were physicochemically characterized and functionally evaluated in vitro. Antitumor efficacy was quantified in vivo using 4T1 breast cancer and K-Ras(LSL/+)/Pten(fl/fl) ovarian cancer models, with effects on glucose homeostasis evaluated using an insulin sensitivity test. The use of PI103 and PI828 as surrogate molecules to engineer the SNPs highlighted the need to keep design principles in perspective; specifically, potency of the active molecule and the linker chemistry were critical principles for efficacy, similar to antibody-drug conjugates. We found that the SNPs exerted a temporally sustained inhibition of phosphorylation of Akt, mTOR, S6K, and 4EBP in vivo. These effects were associated with increased antitumor efficacy and survival as compared with PI103 and PI828. Efficacy was further increased by decorating the nanoparticle surface with tumor-homing peptides. Notably, the use of SNPs abrogated the insulin resistance that has been associated widely with other PI3K inhibitors. This study provides a preclinical foundation for the use of supramolecular nanochemistry to overcome current challenges associated with PI3K inhibitors, offering a paradigm for extension to other molecularly targeted therapeutics being explored for cancer treatment. (C)2013 AACR.

Surface chemistry and growth mechanism of highly oriented, single crystalline TiO2 nanorods on transparent conducting oxide coated glass substrates - Sadhu, Subha; Jaiswal, Adhish; Adyanthaya, Suguna D.; Poddar, Pankaj (RSC Advances, 2013)
The fabrication of one-dimensional (1D) rods or wires of titania in desired crystalline facets is quite exciting due to unique optoelectronic properties. The single crystalline, oriented nanorods directly grown on transparent conducting oxide (TCO) substrates are finding a lot of interest in solar photovoltaics and several other optoelectronic devices due to enhanced electron transport and lower exciton recombination rates. However, the growth of desired crystalline facets of highly oriented, single crystalline nanorods on different substrates and understanding the interplay between the surface chemistry and growth mechanism still remain a non-trivial and challenging task. Here, for the first time, the kinetically controlled growth of the (310) facet of TiO2 nanorods on fluorine-doped tin oxide (FTO) coated glass substrate has been reported which is in contrast to the previously reported (002) faceted TiO2 nanorods. In addition to this, the growth of (110) facet TiO2 nanorods using amorphous fluorine doped silicon oxide (FSO) as a substrate is also demonstrated. In this paper, it is shown that two different faceted TiO2 nanorods can be synthesized following same synthetic condition by varying only the material properties of the substrate. To investigate the role of substrate chemistry on the morphology and single crystallinity of TiO2 nanorods, electron microscopy, XPS and contact angle measurements have been done. The results clearly indicate an important link between the surface chemistry and morphology of TiO2 nanorods. It can be assumed that there is a role of OH- and water groups which are responsible for the growth of plane (110) which has less surface energy. The observation of (310) facet is quite surprising and can be explained based on FTO crystallinity. It is possible to tune the diameter of the titania nanorods by further coating the FTO substrate with a thin gold layer due to increase in the hydrophilicity of the substrate. Finally, a light to electricity conversion efficiency of 2.5% could be achieved by using vertically grown titania nanorods on FTO as the photoanode in a dye sensitized solar cell (DSSC).

Surface induced collapse of A beta(1-42) with the F19A replacement following adsorption on a single walled carbon nanotube - Jana, Asis K.; Sengupta, Neelanjana (Biophysical Chemistry, 2013)
Spontaneous adsorption of the A beta peptide on the surface of a single-walled carbon nanotube, resulting in the prevention of its intrinsic propensity to form collapsed states, could be a plausible means to hinder the peptide's initial nucleation and self-assembly. We report here the effects of sharply reducing both aromatic and hydrophobic character within the peptide's central hydrophobic core on its free and surface behavior. In such an altered peptide, complete surface adsorption is found to induce, rather than prevent, the adsorbed peptide's collapse. The weakened surface interactions of the central hydrophobic core allow its greater translational mobility on the surface, thereby facilitating interactions that lead to compaction. Both the adsorption and the subsequent collapse are accompanied by a loss of surface hydration in the modified peptide. We further find that such a two-step dewetting leads to hydration levels comparable to that obtained after compaction of the free peptide. These insights may be leveraged for designing molecular surfaces for disrupting intrinsic A beta behavior. (C) 2013 Elsevier B.V. All rights reserved.
Keywords: Adsorption; Amyloid beta peptide; carbon nanotube; Lateral mobility; molecular dynamics simulation; Surface induced collapse

Surfactant-free synthesis of anisotropic gold nanostructures: can dicarboxylic acids alone act as shape directing agents? - Kumar, D. V. Ravi; Kumavat, S. R.; Chamundeswari, V. N.; Patra, Partha Pratim; Kulkarni, A. A.; Bhagavatula L. V. Prasad (RSC Advances, 2013)
The present study describes the synthesis of gold nanostructures using different dicarboxylic (viz. oxalic, malonic, succinic, glutaric and adipic) acids as reducing agents in the absence of any other additives or surfactants. Various anisotropic structures such as kites, tadpoles, triangular/hexagonal plates, and twinned particles were seen to evolve depending on the molar ratio of dicarboxylic acid to HAuCl4 used. It was also demonstrated that gold nanostructure formation is hampered as the chain length/distance between two carboxylic acid groups increases. Among the various structures obtained the kite like structures displayed the largest surface enhanced Raman enhancement factors.

Sustainable materials based on aliphatic polyesters: teaching old chemistry some new tricks - Sivaram, S. (Current Science, 2013)

Suzuki-Miyaura cross-coupling reaction between aryl halides and phenylboronic acids over gold nano-particles supported on MgO (or CaO) and other metal oxides - Dumbre, Deepa K.; Yadav, P. N.; Bhargava, Suresh Kumar; Choudhary, Vasant R. (Journal of Catalysis, 2013)
Gold nano-particles-supported alkaline earth metal oxides, particularly MgO or CaO, show high catalytic activity in the Suzuki-Miyaura cross-coupling reaction in the presence of K2CO3 and DMF (as a solvent). The catalytic activity is strongly influenced by the nature or type of metal oxide support (viz, alkaline earth oxide, Group IIIA metal oxide, transition metal oxide, or rare earth oxide actinide oxide). It is also strongly influenced by the nature of aryl halide (aryl iodide, bromide, chloride, or fluoride), amount of K2CO3 in the reaction mixture and catalyst calcination temperature. Influence of reaction parameters viz, temperature and time and different substituents in aryl halides and/or phenylboronic acids on the biphenyl product yield in the reaction over Au/MgO catalyst has also been investigated. The catalyst showed excellent reusability in the reaction. Moreover, it is ligand-free and also has much lower cost than the commonly used homogeneous and heterogeneous Pd catalysts. (C) 2013 Elsevier Inc. All rights reserved.
Keywords: Aryl halides; Au/MgO (or CaO) catalyst; Biphenyls; Gold nano-particles; phenylboronic acids; Suzuki-Miyaura coupling reaction

Switching the H-bonding network of a foldamer by modulating the backbone chirality and constitutional ratio of amino acids - Ramesh, Veera V. E.; Vijayadas, Kuruppanthara N.; Dhokale, Snehal A.; Gonnade, Rajesh G.; Rajamohanan, Pattuparambil R.; Sanjayan, Gangadhar J. (Organic & Biomolecular Chemistry, 2013)
This communication describes the folding propensity of a hetero-foldamer motif featuring proline (Pro) and anthranilic acid (Ant) residues in a 1:2:1 (alpha: beta: alpha) constitutional ratio. Structural investigations unequivocally suggest that the hydrogen-bonding network of this foldamer motif can be switched between 9-membered and 6-membered by modulating the backbone chirality and constitutional ratio of the amino acid residues.

Synergetic effect of combination of AOP's (hydrodynamic cavitation and H2O2) on the degradation of neonicotinoid class of insecticide - Raut-Jadhav, Sunita; Saharan, Virendra Kumar; Pinjari, Dipak; Sonawane, Shirish; Saini, Daulat; Pandit, Aniruddha (Journal of Hazardous Materials, 2013)
In the present work, degradation of imidacloprid (neonicotinoid class of insecticide) in aqueous solution has been systematically investigated using hydrodynamic cavitation and combination of hydrodynamic cavitation (HC) and H2O2. Initially, effect of different operating parameters such as inlet pressure to the cavitating device (5-20 bar) and operating pH (2-7.5) has been investigated. Optimization of process parameters was followed by the study of effect of combination of HC and H2O2 process on the rate of degradation of imidacloprid. Significant enhancement in the rate of degradation of imidacloprid has been observed using HC+H2O2 process which lead to a complete degradation of imidacloprid in 45 min of operation using optimal molar ratio of imidacloprid:H2O2 as 1:40. Substantial synergetic effect has been observed using HC+H2O2 process which confer the synergetic coefficient of 22.79. An attempt has been made to investigate and compare the energy efficiency and extent of mineralization of individual and combined processes applied in the present work. Identification of the byproducts formed during degradation of imidacloprid has also been done using LC-MS analysis. The present work has established a fact that hydrodynamic cavitation in combination with H2O2 can be effectively used for degradation of imidacloprid. (C) 2013 Elsevier B.V. All rights reserved.
Keywords: Advanced oxidation processes; Hydrodynamic cavitation; Imidacloprid; Synergetic coefficient; Venturi

Synergistic action of flavin containing NADH dependant azoreductase and cytochrome P450 monooxygenase in azoaromatic mineralization - Oturkar, Chetan C.; Othman, Munif A.; Kulkarni, Mahesh J.; Madamwar, Datta; Gawai, Kachru R. (RSC Advances, 2013)
An alkaliphilic strain Bacillus lentus Bl377 was isolated from contaminated soil of the textile area of Solapur, India. The strain was able to degrade almost 98% of recalcitrant azoic compounds by a mutually regulated process of azoreductase and a monooxygenase system. An enzyme activity study and a periodical carbon monoxide (CO) binding spectra study on a UV-visible spectrophotometer revealed that the intermediate amines formed by typical azoreduction (N=N cleavage), subsequently underwent hydroxylation by the cytochrome P450 monooxygenase (CYP450) system. Azoreductase was purified by chromatographic techniques and characterization by MALDI-TOF substantiated its identity as FMN containing NADH dependent azoreductase of 32 kDa in size. Surprisingly, purified azoreductase showed the highest activity at 80 degrees C and pH 8.0. An increase in the activity of superoxide dismutase after decolorization confirmed the signature of oxidative stress and its involvement in the dismutation of reactive metabolites. Intermediate metabolite analysis by HPLC, GC-MS and FTIR and the removal of total organic carbon (TOC) suggested the azoaromatics' degradation leads to mineralization via a TCA cycle.

Synergistic mechanical response of Nylon 6/Trogamid (R) T blends - Ridhore, Amol; Jog, Jyoti Prakash (Journal of Applied Polymer Science, 2013)
Blends of semicrystalline Nylon 6 with a varying ratios of amorphous Nylon are studied for their morphological, thermal, dielectric, and mechanical behavior. Thermal analysis indicated a compositional dependant decrease in the melting and crystallization temperatures of Nylon 6. The blends exhibited a single compositional dependant glass transition temperature in dynamic mechanical thermal analysis and dielectrical relaxation spectroscopy over entire mixing ratio indicating miscibility between the blend components. The values of flexural modulus and tensile modulus of the blends are found to increase without significant loss in the impact properties. The water absorption of the blends is also lower than the values calculated by rule of mixtures. The observed synergistic behavior of the mechanical properties of the blends is indicative of presence of strong interactions in the blends components. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Keywords: blends; dielectric properties; mechanical properties; polyamides; Thermal properties

Syntheses and determination of absolute configurations and biological activities of the enantiomers of the longtailed mealybug pheromone - Ramesh, Remya; Swaroop, Pandrangi Siva; Gonnade, Rajesh G.; Thirupath, Choppari; Waterworth, Rebeccah A.; Millar, Jocelyn G.; Reddy, D. Srinivasa (Journal of Organic Chemistry, 2013)
Preparation and assignment of absolute configurations to both enantiomers of the sex pheromone of the longtailed mealybug, an irregular monoterpenoid with extraordinary biological activity, has been completed. Comparison of the biological activities of both enantiomers and the racemate in field trials showed that the (S)-(+)-enantiomer was highly attractive to male mealybugs, strongly suggesting that female longtailed mealybugs produce this enantiomer. The (R)-(-)-enantiomer was benign, being neither attractive nor inhibitory.

Synthesis and antimicrobial activity of novel oxysterols from lanosterol - Shingate, Bapurao B.; Hazra, Braja G.; Salunke, Deepak B.; Pore, Vandana S.; Shirazi, Fazal; Deshpande, Mukund V. (Tetrahedron, 2013)
Chemically diverse oxysterols and their synthetic manipulations were carried out from variety of Delta(8(9)_) lanosterol derivatives and evaluated for their in vitro antimicrobial activities. Most of the synthesized oxysterols exhibited significant antifungal activity against the tested strains. (C) 2013 Elsevier Ltd. All rights reserved.
Keywords: Allylic oxidation; antibacterial activity; Antifungal activity; Dihydroxylation; Oxygenated steroids

Synthesis and antitubercular activity of amino alcohol fused spirochromone conjugates - Mujahid, Mohammad; Gonnade, Rajesh G.; Yogeeswari, P.; Sriram, D.; Muthukrishnan, Murugan (Bioorganic & Medicinal Chemistry Letters, 2013)
A series of 21 new amino alcohol fused spirochromone conjugates have been synthesized, characterized with analytical data and evaluated their antimycobacterial activity against Mycobacterium tuberculosis (virulent strain H37Rv) in vitro. Some of the compounds exerted significant inhibition, in particular, compound 4f found to be the most potent derivative exhibiting MIC = 3.13 mu g/mL. (C) 2013 Elsevier Ltd. All rights reserved.
Keywords: Amino alcohol; Antitubercular activity; Mycobacterium tuberculosis; Spirochromones

Synthesis and catalytic activity of monodisperse gold-mesoporous silica core-shell nanocatalysts - Sekhar, A. C. Sunil; Meera, C. J.; Kottavarithottil Ziyad; Gopinath, Chinnakonda S.; Vinod, C. P. (Catalysis Science & Technology, 2013)
Core-shell nanostructures, where gold nanoparticles of sub 10 nm size are successfully encapsulated inside porous silica spheres, have been prepared. The detailed characterization of the catalyst shows a high surface area and good mesoporosity. The sinter resistance of the catalyst under repeated cycles of the CO oxidation reaction is observed.

Synthesis and characterization of poly(ether ether ketone)s and poly(ether ether ketone ketone) s containing pendant biphenyl and naphthyl groups - Honkhambe, Pandurang N.; Dhamdhere, Neelam A.; Tawade, Bhausaheb V.; Salunkhe, Manikrao M.; Wadgaonkar, Prakash P. (High Performance Polymers, 2013)
New poly(ether ether ketone)s (PEEKs) and poly(ether ether ketone ketone)s (PEEKKs) containing pendant biphenyl and naphthyl groups were synthesized by nucleophilic substitution reaction of each of the four bisphenols viz., 1-(4- biphenylyl)- 1,1- bis(4- hydroxyphenyl) ethane, 1-(4- biphenylyl)- 1,1- bis(3- methyl, 4- hydroxyphenyl) ethane, 4,4'-[1-(2- naphthalenyl) ethylidene] bis-phenol and 4,4'-[1-(2- naphthalenyl) ethylidene] bis-3-methylphenol with 4,4'- difluorobenzophenone and 1,3- bis(4- fluorobenzoyl) benzene in a solvent mixture of N,N-dimethylacetamide and toluene in the presence of anhydrous potassium carbonate. Inherent viscosities and number-average molecular weights of polymers were in the range of 0.42-0.86 dl/g and 2.40-7.55 x 10(4), respectively. PEEKs and PEEKKs were amorphous in nature and were readily soluble in a wide range of organic solvents and could be cast into flexible and tough films from chloroform solution. Glass transition temperature of PEEKs and PEEKKs were in the range of 180 degrees C -200 degrees C. T-10 values of PEEKs and PEEKKs were in the range of 424 degrees C-512 degrees C in nitrogen atmosphere, indicating their good thermal stability.
Keywords: biphenyl; bisphenol; naphthyl; poly(ether ether ketone ketone)s; poly(ether ether ketone)s; Polycondensation; Thermal properties

Synthesis and electrochemical performance of a single walled carbon nanohorn-Fe3O4 nanocomposite supercapacitor electrode - Deshmukh, Ashvini B.; Shelke, Manjusha V. (RSC Advances, 2013)
A new Fe3O4-SWCNH nanocomposite was synthesized as an electrode material for supercapacitors. The nanocomposite exhibited a high specific capacitance of 377 F g(-1) and delivered a stable discharge capacitance at a current density of 1 A g(-1) over 1000 cycles between 0 and 1.2 V.

Synthesis and fluorescence properties of a full set of extended RNA base analogues - Sabale, Pramod M.; Nuthanakanti, Ashok; Srivatsan, Seergazhi G. (Indian Journal of Chemistry Section A-Inorganic Bio-Inorganic Physical Theoretical & Analytical Chemistry, 2013)
The synthesis and photophysical characterization of a complete set of fluorescent RNA base analogues derived by conjugating benzofuran moiety at the 5- and 8-positions of pyrimidine and purine bases, respectively, are described. Benzofuran-modified pyrimidine and purine ribonucleoside analogues exhibit Contrasting fluorescence properties. Pyrimidine analogues are moderately emissive with emission maximum in the visible region, and importantly, are highly sensitive to solvent polarity and Viscosity changes. On the other hand, purine analogues are highly emissive and are minimally affected by solvation. and viscosity effects. Thorough photophysical analysis reveals that the pyrimidine and purine ribonucleosides displaying distinct and-probe-like fluorescence properties could be useful in designing nucleic acid based biophysical tools to study nucleic acid structure and function.
Keywords: Environment sensitive probes; Fluorescence probes; Fluorescence spectroscopy; Nucleic acids; Ribonucleoside analogues

Synthesis and molecular structure of a zinc complex of the vitamin K-3 analogue phthiocol - Kathawate, Laxmi; Sproules, Stephen; Pawar, Omkar; Markad, Ganesh; Haram, Santosh K.; Puranik, Vedavati G.; Salunke-Gawali, Sunita (Journal of Molecular Structure, 2013)
The complex [Zn(phthiocol)(2)(H2O)(2)]; 1, where phthiocol is 2-hydroxy-3-methyl-1,4-naphthoquinone, has been synthesized and characterized by elemental analysis, FT-IR, H-1 NMR, UV-vis spectroscopy, thermogravimetric (TG) analysis, electrochemical and single crystal X-ray diffraction studies. The v(C=O) stretch shifts to lower frequencies upon complexation of phthiocol to Zn2+. H-1 NMR spectra show an upfield shift of the benzenoid ring protons in 1. There is a bathochromic shift of the LMCT band in the UV-vis spectra of 1. Single crystal X-ray structure of 1 show distorted octahedral geometry around Zn2+. Two phthiocol ligands are in plane with the metal, while water molecules are trans to this plane. Coordination of deprotonated phthiocol ligands is `trans, trans' to Zn2+. Intra as well as intermolecular interactions are observed in 1. Molecules of 1 show three dimensional network through C-H center dot center dot center dot O and O-H center dot center dot center dot O interactions. Additional anodic peaks are observed in cyclic voltammogram of phthiocol ligand due to oxidation of reduced species formed during reduction. One-electron reduction of 1 is shown to be reversible and DFT studies define this redox event as ligand-centered. (c) 2013 Elsevier B.V. All rights reserved.
Keywords: hydrogen bonding; Naphthoquinone; Phthiocol; Trans coordination; Vitamin K-3; Zinc complex

Synthesis and properties of 2 `-O-[R- and S-(2-amino-3-methoxy)propyl] (R-AMP and S-AMP) nucleic acids - Kotikam, Venubabu; Kumar, Vaijayanti A. (Tetrahedron, 2013)
Substitution at 2'-position by either amino- or methoxy-pendant groups of the antisense oligonucleotides (AONs) is known to enhance their therapeutic value. A simple modification is described here in which we introduce both these groups in the form of enantiospecific tethers at 2'-position. Practical synthesis of modified nucleosides using natural L-serine, en route to R-AMP- and S-AMP-AONs is presented. Such tethered ONs formed stable DNA:RNA duplexes and the stability was found to be marginally better than the methoxyethyl/methoxypropyl-substituted MOE/MOP-AONs. The stereochemistry of the tether effectively differentiated the hydrolytic cleavage of AONs and the R-AMP-AON was three times more stable than the S-AMP-AONs after 4 h. In comparison, the MOE- or MOP-AONs were almost completely digested by SVPD after 1 h. (C) 2013 Elsevier Ltd. All rights reserved.
Keywords: Antisense therapeutics; MOE-AONs; Positively charged ON analogues

Synthesis and self-assembly of amphiphilic homoglycopolypeptide - Dhaware, Vinita; Shaikh, Ashif Y.; Kar, Mrityunjoy; Hotha, Srinivas; Sen Gupta, Sayam (Langmuir, 2013)
The synthesis of the amphiphilic homoglycopolypeptide was carried out by a combination of NCA polymerization and click chemistry to yield a well-defined Polypeptide having an amphiphilic carbohydrate on its side chain. The amphiphilicity of the carbohydrate was achieved by incorporation of an alkyl chain, at the C-6 position of the carbohydrate thus also rendering the homoglycopolypeptide amphiphilic. The homoglycopolypeptide formed multimicellar aggregates in water above a critical concentration of 0.9 mu M due to phase separation. The multimicellar aggregates were characterized by DLS, TEM, and AFM. It is proposed that hydrophobic interactions of the aliphatic chains at the 6-position of the sugar moieties drives the assembly of these rod-like homoglycopolypeptide into large;spherical aggregates. These multimicellar aggregates encapsulate both hydrophilic as well as hydrophobic dye as was confirmed by confocal microscopy. finally, amphiphilic random polypeptides containing 10% and 20% alpha-D-mannose in addition to glucose containing a, hydrophobic alkyl chain at its 6 position were synthesized by our methodology, and these polymers Were also found to assemble into spherical nanostructures. The spherical assemblies Of amphiphilic random glycopolypeptides containing 10% and 20% mannose were found to be surface bioactive and were found, to interact with the lectin Con-A.

Synthesis and structural studies of S-type/N-type-locked/frozen nucleoside analogues and their incorporation in RNA-selective, nuclease resistant 2 `-5 ` linked oligonucleotides - Erande, Namrata D.; Gunjal, Anita D.; Fernandes, Moneesha; Gonnade, Rajesh G.; Kumar, Vaijayanti A. (Organic & Biomolecular Chemistry, 2013)
2'-endo locked or frozen (S-type)/3'-endo locked or frozen (N-type) nucleoside analogues were synthesized. Conformational analysis based on (3)J(HH) and NOE measurements is presented which is further confirmed by X-ray crystal structural studies. 2'-5' isoDNA oligonucleotides (ON) were synthesized using these modified nucleoside analogues and UV-T-m studies of the resultant 2'-5' isoDNA : RNA duplexes reflect the site-and sequence-dependent effects and confirm that the S-type sugar conformations were preferred over the N-type sugar geometry in such duplexes.

Synthesis and X-ray single crystal structure of a cadmium(II) acetophenone thiosemicarbazone complex and its use as a single-source precursor for the preparation of CdS nanocrystallites and thin films - Palve, Anil M.; Joshi, Pranaya V.; Puranik, Vedavati G.; Garje, Shivram S. (Polyhedron, 2013)
{A cadmium(II) acetophenone thiosemicarbazone complex has been prepared and characterized by elemental analysis, infrared and nuclear magnetic resonance (H-1 and C-13H-1) spectroscopic techniques. Its single crystal structure has also been determined. The compound is found to be monoclinic, space group C2/c, with a = 12.1020(3) angstrom
Keywords: CdS; Nanocrystallites; Single source precursor; Thin films; Thiosemicarbazone complex

Synthesis of 3,5-Bis(acrylaldehyde) boron-dipyrromethene and application in detection of cysteine and homocysteine in living cells - Madhu, Sheri; Gonnade, Rajesh G.; Ravikanth, Mangalampalli (Journal Of Organic Chemistry, 2013)
Synthesis, characterization, and spectral and electrochemical properties of 3,5-bis(acrylaldehyde) BODIPY are described. The compound exhibited higher selectivity toward cysteine/homocysteine than toward other amino acids and thiol-containing compounds as shown by absorption and emission titration experiments and by experiments in living cells.

Synthesis of a sex pheromone of the longtailed mealybug, pseudococcus longispinus - Kurhade, Suresh E.; Siddaiah, V.; Bhuniya, Debnath; Reddy, D. Srinivasa (Synthesis-Stuttgart, 2013)
The synthesis of a recently identified and highly active sex pheromone of the longtailed mealybug, Pseudococcus longispinus is reported. A concise synthetic route, use of the under explored Meyer-Schuster rearrangement, Claisen rearrangement, and ring-closing metathesis are the highlights of this work.
Keywords: Acylation; Metathesis; pheromones; rearrangement; Total synthesis

Synthesis of Ag-glyconanoparticles using C-glycosides, their lectin binding studies and antibacterial activity - Ramtenki, Vilas; Raju, D.; Mehta, Urmil J.; Ramana, C. V.; Bhagavatula L. V. Prasad (New Journal of Chemistry, 2013)
Two 12-C-glycosyl dodecanoic acids, namely, 1-(alpha-D-mannopyranosyl)-12-dodecanoic acid and 1-(alpha-D-glucopyranosyl)-12-dodecanoic acid were synthesized. Their ability to act as reducing and capping agents for the synthesis of water re-dispersible silver nanoparticles is displayed. These Ag C-glycosyl nanoparticles were later utilized to investigate the carbohydrate-lectin interactions. Furthermore, the specificity of mannoside binding to the surface of the Gram negative bacterium Escherichia coli has been utilized to demonstrate the enhanced antibacterial activity of Ag-C-mannosyl nanoparticles towards this bacterium as compared to Ag-C-glycosyl nanoparticles.

Synthesis of all four nucleoside-based beta-amino acids as protected precursors for the synthesis of polyamide-DNA with alternating alpha-amino acid and nucleoside-beta-amino acids - Seema Bagmare; Varada, Manojkumar; Banerjee, Anjan; Kumar, Vaijayanti A. (Tetrahedron, 2013)
A simple approach is described for the synthesis of all four orthogonally protected nucleoside-beta-amino acids from commercially available starting materials. Synthesis of a model tetrameric DNA sequence in 5'-3'direction employing trityl strategy and glycine as alpha-amino acid alternating with nucleoside-beta amino acids is described. (C) 2012 Elsevier Ltd. All rights reserved.
Keywords: Antisense therapeutics; Neutral DNA analogues; Nucleoside-beta amino acids

Synthesis of C(27)–C(38) fragment of aflastatin A - Narute, Sachin B.; Ramana, C.V. (Tetrahedron, 2013)
Efforts at finding out a strategy for the synthesis of the densely hydroxylated C(27)–C(48) fragment of aflastatin A have been described. The initial studies dealing with alkyne–epoxide coupling using a linear polyol epoxide resulted in a debenzylative cycloetherification leading to a C-arabinoside derivative. This problem has been addressed by applying an epoxide pendant on a furanosyl unit. With the model alkyne, the epoxide–alkyne coupling proceeded smoothly. Subsequently, following a sequence of [Pd]-mediated alkynone cycloisomerization/stereoselective hydroboration–oxidation, the synthesis of the central C(27)–C(38) fragment has been executed. When employed, the original C(33)–C(48) alkyne, the coupling and the cycloisomerizations are facile. However, the resulting glycals are unstable, thus warranting a revision in our approach.
Keywords: Aflastatin; Epoxide–alkyne coupling; ω-Alkynone cycloisomerization; Palladium catalysis; Hydroboration

Synthesis of C-disaccharides through a one-pot alkynol cycloisomerization-reductive deoxygenation - Narute, Sachin B.; Rout, Jeetendra Kumar; Ramana, Chepuri V. (Chemistry-A European Journal, 2013)
Keywords: C-disaccharides; carbohydrates; Epoxide-alkyne coupling; Gold catalysis; Reductive deoxygenation

Synthesis of end-functionalized phosphate and phosphonate-polypeptides by ring-opening polymerization of their corresponding N-carboxyanhydride - Das, Soumen; Kar, Mrityunjoy; Sen Gupta, Sayam (Polymer Chemistry, 2013)
Phosphopolypeptides provide an interesting biomimetic analog for phosphorylated proteins that are involved in biomineralization. We have developed a high yielding synthesis of cysteine-based phosphate and phosphonate N-carboxyanhydride (NCA) by using the thiol-ene coupling reaction. These phosphate and phosphonate NCA monomers underwent polymerization using simple primary amine initiators to form well defined homophosphopolypeptides. Using a bifunctional initiator we were able to install a ``clickable'' alkyne or azide group at the end of the polypeptide chain. We were also able to successfully synthesize fully water-soluble phosphonate based polypeptides by hydrolysis of the corresponding phosphonate ester groups in the polypeptide. These water-soluble phosphopolypeptides adopt a random coil conformation at physiological pH.

Synthesis of indolizidine, pyrrolizidine and quinolizidine ring systems by proline-catalyzed sequential alpha-amination and HWE olefination of an aldehyde - Kauloorkar, Shruti Vandana; Jha, Vishwajeet; Kumar, Pradeep (RSC Advances, 2013)
A general procedure for the synthesis of azabicyclic ring systems viz. indolizidine, pyrrolizidine and quinolizidine has been developed utilizing proline-catalyzed sequential alpha-amination and Horner-Wadsworth-Emmons (HWE) olefination of an aldehyde as the key step. This method can be further extended to the synthesis of various biologically active natural products containing azabicyclic ring systems.

Synthesis of low coercive BaFe12O19 hexaferrite for microwave applications in low-temperature cofired ceramic - Rane, Vivek A.; Meena, Sher Singh; Gokhale, Suresh P.; Yusuf, S. M.; Phatak, Girish J.; Date, Sadgopal K. (Journal of Electronic Materials, 2013)
Polycrystalline M-type barium hexaferrite (BaFe12O19) samples have been synthesized by solution combustion route at different pH and calcination conditions in order to reduce the coercivity for microwave applications in low-temperature cofired ceramic (LTCC) substrates. Structural, morphological, and magnetic properties of BaFe12O19 were studied by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Raman spectroscopy, vibrating sample magnetometry (VSM), and Mossbauer spectroscopy. The formation of a single-phase hexagonal structure was confirmed by XRD. The Raman spectra reveal all characteristic peaks of BaFe12O19, illustrating the phase purity and crystal lattice symmetry of the synthesized material. Mossbauer spectra illustrate the existence of Fe3+ cations at all five crystallographic lattice sites. The microstructural features observed by FESEM disclose the growth of nanoregime particles into hexagonal platelet particles after calcination at temperatures from 800A degrees C to 1200A degrees C. The VSM results show a lower coercivity (1350 Oe to 3500 Oe) together with reasonably high saturation magnetization (55 emu/g to 60 emu/g) and a high bulk resistivity (> 10(9) Omega-cm) at room temperature. The dependence of magnetic and electrical properties on the preparation and processing conditions is also discussed.
Keywords: Barium hexaferrite; coercivity; LTCC; Mossbauer spectroscopy; Raman spectroscopy

Synthesis of palmyrolide A and its cis-isomer and mechanistic insight into trans-cis isomerisation of the enamide macrocycle - Philkhana, Satish Chandra; Seetharamsingh, B.; Dangat, Yuvraj B.; Vanka, Kumar; Reddy, D. Srinivasa (Chemical Communications, 2013)
Concise and protecting-group free synthesis of ent-palmyrolide A and (-)-cis-palmyrolide A were achieved starting from commercially available (S)-citronellal. The key fragment of palmyrolide A, ``(5S,7S)-7-hydroxy-5,8,8-trimethylnonanamide'', which makes up the most challenging part of the target molecule, was prepared in just three steps. A plausible mechanism for the trans-cis isomerization of the double bond in the macrocycle has been investigated.

Synthesis of pseudo-indoxyl derivatives via sequential Cu-catalyzed SNAr and Smalley cyclization - Goriya, Yogesh; Ramana, Chepuri V. (Chemical Communications, 2013)
ortho-Bromophenyl sec-alkyl/sec-alkenyl ketones, on reaction with sodium azide in the presence of copper salts, undergo sequential SNAr followed by Smalley cyclization to provide pseudo-indoxyl derivatives. Some of these pseudo-indoxyl derivatives exhibit interesting fluorescent properties and broad Stokes shifts.

Synthesis of triangular gold nanoplates: role of bromide ion and temperature - Kumar, D. V. Ravi; Kulkarni, Amol A.; Bhagavatula L. V. Prasad (Colloids and Surfaces A-Physicochemical and Engineering Aspects, 2013)
Synthesis of noble metal triangular nanoplates is a kinetically controlled process in which temperature and packing defects play a major role. Nucleation and growth process of kinetically controlled reaction can be greatly influenced by temperature affecting the yield and edge length of the triangles. Through a conventional batch mode process, here we study the effect of temperature on nucleation and growth of gold triangular nanoplates and obtain some insight of the temperature effects on the final yield and edge length of triangles. The role of Br- ions in the synthesis of triangular nanoplates is studied by varying the amount of CAB and by replacing the CTAB with HBr. The results show that, while CTAB controls the edge length and yield of triangles, its use is not mandatory to attain plate like morphology. Finally we show that, while the initial temperature of the reaction mixture governs the nucleation rate and the rate of temperature rise governs the growth rate of particles, they along with the concentration of Br- ions control the edge length and yield. (C) 2013 Elsevier B.V. All rights reserved.
Keywords: Au nanotriangles; Halide ion effect; heat transfer; Kinetically controlled; Nature of gold precursor complex; Nucleation and growth; Optical properties

Synthesis, steady-state, and femtosecond transient absorption studies of resorcinol bound ruthenium(ii)- and osmium(ii)-polypyridyl complexes on nano-TiO2 surface in water - Banerjee, Tanmay; Kaniyankandy, Sreejith; Das, Amitava; Ghosh, Hirendra Nath (Inorganic Chemistry, 2013)
The synthesis of two new ruthenium(II)- and osmium(II)-polypyridyl complexes 3 and 4, respectively, with resorcinol as the enediol anchoring moiety, is described. Steady-state photochemical and electrochemical studies of the two sensitizer dyes confirm strong binding of the dyes to TiO2 in water. Femtosecond transient absorption studies have been carried out on the dye–TiO2 systems in water to reveal <120 fs and 1.5 ps electron injection times along with 30% slower back electron transfer time for the ruthenium complex 3. However, the corresponding osmium complex 4 shows strikingly different behavior for which only a <120 fs ultrafast injection is observed. Most remarkably, the back electron transfer is faster as compared to the corresponding catechol analogue of the dye. The origin and the consequences of such profound effects on the ultrafast interfacial dynamics are discussed. This Article on the electron transfer dynamics of the aforesaid systems reinforces the possibility of resorcinol being explored and developed as an extremely efficient binding moiety for use in dye-sensitized solar cells.

Synthesis, structure, and H-2/CO2 adsorption in a three-dimensional 4-connected triorganotin coordination polymer with a sqc topology - Chandrasekhar, Vadapalli; Mohapatra, Chandrajeet; Banerjee, Rahul; Mallick, Arijit (Inorganic Chemistry, 2013)
A 4-connected triorganotin 3D coordination polymer in a sqc topology has been shown to possess 1D microchannels along its crystallographic a axis. This main-group-element-containing framework structure shows selective gas adsorption, preferring CO2 and H-2 over N-2.

Synthesis, structures, and dearomatization by deprotonation of iron complexes featuring bipyridine-based PNN pincer ligands - Zell, Thomas; Langer, Robert; Iron, Mark A.; Konstantinovski, Leonid; Shimon, Linda J. W.; Diskin-Posner, Yael; Leitus, Gregory; Balaraman, Ekambaram; Ben-David, Yehoshoa; Milstein, David (Inorganic Chemistry, 2013)
The synthesis and characterization of new iron pincer complexes bearing bipyridine-based PNN ligands is reported. Three phosphine-substituted pincer ligands, namely, the known tBu-PNN (6-((di-tert-butylphosphino)methyl)-2,2′-bipyridine) and the two new iPr-PNN (6-((di-iso-propylphosphino)methyl)-2,2′-bipyridine) and Ph-PNN (6-((diphenylphosphino)methyl)-2,2′-bipyridine) ligands were synthesized and studied in ligation reactions with iron(II) chloride and bromide. These reactions lead to the formation of two types of complexes: mono-chelated neutral complexes of the type [(R-PNN)Fe(X)2] and bis-chelated dicationic complexes of the type [(R-PNN)2Fe]2+. The complexes [(R-PNN)Fe(X)2] (1: R = tBu, X = Cl, 2: R = tBu, X = Br, 3: R = iPr, X = Cl, and 4: R = iPr, X = Br) are readily prepared from reactions of FeX2 with the free R-PNN ligand in a 1:1 ratio. Magnetic susceptibility measurements show that these complexes have a high-spin ground state (S = 2) at room temperature. Employing a 2-fold or higher excess of iPr-PNN, diamagnetic hexacoordinated dicationic complexes of the type [(iPr-PNN)2Fe](X)2 (5: X = Cl, and 6: X = Br) are formed. The reactions of Ph-PNN with FeX2 in a 1:1 ratio lead to similar complexes of the type [(Ph-PNN)2Fe](FeX4) (7: X = Cl, and 8: X = Br). Single crystal X-ray studies of 1, 2, 4, 6, and 8 do not indicate electron transfer from the FeII centers to the neutral bipyridine unit based on the determined bond lengths. Density functional theory (DFT) calculations were performed to compare the relative energies of the mono- and bis-chelated complexes. The doubly deprotonated complexes [(R-PNN*)2Fe] (9: R = iPr, and 10: R = Ph) were synthesized by reactions of the dicationic complexes 6 and 8 with KOtBu. The dearomatized nature of the central pyridine of the pincer ligand was established by X-ray diffraction analysis of single crystals of 10. Reactivity studies show that 9 and 10 have a slightly different behavior in protonation reactions.

Synthetic zipper peptide motif orchestrated via co-operative interplay of hydrogen bonding, aromatic stacking, and backbone chirality - Nair, Roshna V.; Kheria, Sanjeev; Rayavarapu, Suresh; Kotmale, Amol S.; Jagadeesh, Bharatam; Gonnade, Rajesh G.; Puranik, Vedavati G.; Rajamohanan, Pattuparambil R.; Sanjayan, Gangadhar J. (Journal of the American Chemical Society, 2013)
Here, we report on a new class of synthetic zipper peptide which assumes its three-dimensional zipper-like structure via a co-operative interplay of hydrogen bonding, aromatic stacking, and backbone chirality. Structural studies carried out in both solid- and solution-state confirmed the zipper-like structural architecture assumed by the synthetic peptide which makes use of unusually remote inter-residual hydrogen-bonding and aromatic stacking interactions to attain its shape. The effect of chirality modulation and the extent of noncovalent forces in the structure stabilization have also been comprehensively explored via single-crystal X-ray diffraction and solution-state NMR studies. The results highlight the utility of noncovalent forces in engineering complex synthetic molecules with intriguing structural architectures.

Systematic evaluation of a few proline derivatives as catalysts for a direct aldol reaction - Sutar, Revannath L.; Joshi, Navalkishore N. (Tetrahedron-Asymmetry, 2013)
A series of pyrrolidine derivatives were prepared and examined as catalysts for an aldol reaction. Structural variations in these molecules involved altering the sterics at the alpha-position, the position of the carbonyl group, and the acidities of the hydrogen bonding sites. The effect of these factors on catalytic activity and enantioselectivity was studied. The experimental results revealed that additional sterics at the alpha-position were detrimental. However, no correlation was found between the catalytic activity and N-H acidity. (C) 2012 Elsevier Ltd. All rights reserved.

SBA-15 intercalated Mg-Al hydrotalcite: an environmental friendly catalyst for hydroisomerization of olefin - Baskaran, Thangaraj; Christopher, Jayaraj; Ajithkumar, Thalasseril G.; Sakthivel, Ayyamperumal (Applied Catalysis A-General, 2014)
SBA-15 Molecular sieve-intercalated Mg-Al hydrotalcite (MASBA-HT) was synthesized for the first time by a simple straightforward method. The intercalation of SBA-15 molecular sieve between the interlayer of HT was evident from powder XRD, TEM and FT-IR studies. The presence of SBA-15 facilitates retention of the layered structure for first time, even after calcination at high temperature of 550 degrees C. The resultant material possesses moderate acidity which comes from incorporation of aluminum into the framework of SBA-15 and also contained soluble basicity similar to HT materials. The material shows promising activity for hydroisomerization of 1-octene resulting in good substrate conversion (80%) and branched isomers selectivity (45%). The catalytic activity remains constant over longer duration and repeated runs. (C) 2014 Elsevier B.V. All rights reserved.
Keywords: Branched alkenes; Hydroisomerization; Intercalated-hydrotalcite; layered materials; Mesoporous SBA-15

Scaling behavior of resistive switching in epitaxial bismuth ferrite heterostructures - Rana, Abhimanyu; Lu, Haidong; Bogle, Kashinath A.; Zhang, Qi; Vasudevan, Rama; Thakare, Vishal; Gruverman, Alexei; Ogale, Satishchandra; Valanoor, Nagarajan (Advanced Functional Materials, 2014)
Resistive switching (RS) of (001) epitaxial multiferroic BiFeO3/La0.67Sr0.33MnO3/SrTiO3 heterostructures is investigated for varying lengths scales in both the thickness and lateral directions. Macroscale current-voltage analyses in conjunction with local conduction atomic force microscopy (CAFM) reveal that whilst both the local and global resistive states are strongly driven by polarization direction, the type of conduction mechanism is different for each distinct thickness regime. Electrode-area dependent studies confirm the RS is dominated by an interface mechanism and not by filamentary formation. Furthermore, CAFM maps allow deconvolution of the roles played by domains and domain walls during the RS process. It is shown that the net polarization direction, and not domain walls, controls the conduction process. An interface mechanism based on barrier height and width alteration due to polarization reversal is proposed, and the role of electronic reconstruction at the interface is further investigated.

Scaling up the shape: a novel growth pattern of gallium clusters - Kaware, Vaibhav; Joshi, Kavita (Journal of Chemical Physics, 2014)
Putative global minima for Ga+N clusters with size ``N'' ranging from 49 to 70 are found by employing the Kohn-Sham formulation of the density functional theory, and their evolution is described and discussed in detail. We have discovered a unique growth pattern in these clusters, all of which are hollow core-shell structures. They evolve with size from one spherical core-shell to the next spherical core-shell structure mediated by prolate geometries, with an increase in overall diameter of the core, as well as the shell, without putting on new layers of atoms. We also present a complete picture of bonding in gallium clusters by critically analyzing the molecular orbitals, the electron localization function, and Bader charges. Bonding in these clusters is a mixture of metallic and covalent type that leans towards covalency, accompanied by marginal charge transfer from the surface to the core. Most molecular orbitals of Ga clusters are non-jellium type. Covalency of bonding is supported by a wide localization window of electron localization function, and joining of its basins along the bonds. (C) 2014 AIP Publishing LLC.

Second generation, arginine-rich (R-X `-R)(4)-type cell-penetrating alpha-omega-alpha-peptides with constrained, chiral omega-amino acids (X `) for enhanced cargo delivery into cells - Patil, Kiran M.; Naik, Rangeetha J.; Vij, Manika; Yadav, Amit K.; Kumar, Vaijayanti A.; Ganguli, Munia; Fernandes, Moneesha (Bioorganic & Medicinal Chemistry Letters, 2014)
The syntheses of novel N-aminoalkyl proline-derived spacers (X') in polycationic (R-X'-R)-motif cell-penetrating alpha-omega-alpha-peptides are described as improved molecular transporters and their structural features studied by CD. FACS analysis shows enhanced cellular uptake and confocal microscopy indicates predominantly cytoplasmic localization. The oligomers are efficient at transporting pDNA into cells. The chirality together with the hydrophobicity and flexibility derived from the spacer chain are found to have marked influence on the cell-penetrating and cargo delivery properties of the cell-penetrating peptides (CPPs). The peptides containing N-(3-aminopropyl)-D-proline spacers are found to be the best at cell penetration and cargo delivery in the present study. (C) 2014 Elsevier Ltd. All rights reserved.
Keywords: (R-X-R)-motif; alpha-omega-alpha-Peptide; Cell-penetrating peptide; Constrained chiral amino acid; Peptidomimetics

Selection of phytase producing yeast strains for improved mineral mobilization and dephytinization of chickpea flour - Pable, A.; Gujar, P.; Khire, Jayant Malhar (Journal of Food Biochemistry, 2014)
Among 600 yeast isolates screened for phytase production, five (Zygosaccharomyces bisporusNCIM 3265 and 3296, Williopsis saturnusNCIM 3298, Zygosaccharomyces priorionusNCIM 3299 and Schizosaccharomyces octosporusNCIM 3297) were selected as potential phytase producers. Phytase activity was found to be cell wall associated with temperature and pH optima of 50C and 4.0, respectively. Highest phytase production was attained in cane juice medium as compared with other media used. Addition of phytase to chickpea flour significantly enhanced mineral mobilization by approximately 20-28%, 26-37% and 24-42% for Zn2+, Fe2+ and Ca2+, respectively, and decreased phytic acid content by about 75-88%.

Selective synthesis of propofol (2,6-diisopropylphenol), an intravenous anesthetic drug, by isopropylation of phenol over H-beta and H-mordenite - Nandiwale, Kakasaheb Y.; Bokade, Vijay V. (RSC Advances, 2014)
Propofol (2,6-diisopropylphenol/DIPP) is the world's most widely used intravenous general anesthetic and is typically synthesized by isopropylation of phenol over an acid catalyst. It is highly difficult to stabilize bio-oil containing phenolic compounds. The isopropylation of this phenol (a model compound representing species in bio-oils) is one of the options to stabilize the bio-oil and convert it into valuable products. Probably for the first time, H-beta- and H-mordenite-catalysed vapour phase isopropylation of phenol with isopropyl alcohol (IPA) was studied to selectively synthesize DIPP. The optimization of various operating parameters such as molar ratio (phenol : IPA), weight hourly space velocity (WHSV), reaction temperature and time on stream were performed. H-beta (94% phenol conv. and 56% DIPP sel.) was found to be a potential and more active catalyst than H-mordenite (68% phenol conv. and 43% DIPP sel.) at optimized process parameters. A kinetic model is proposed to probe the intricate reaction kinetics and validated (R-2 > 0.98) by the experimental results. H-beta catalyst was observed to be stable for more than 25 h with 94% phenol conversion and 56% selectivity towards DIPP at optimized process parameters. The phenol conversion and DIPP selectivity obtained in the present study are higher than those reported so far. The activation energy obtained for isopropylation of phenol with IPA over H-beta is calculated to be 25.39 kJ mol(-1).

Sequential electrochemical unzipping of single-walled carbon nanotubes to graphene ribbons revealed by in situ Raman spectroscopy and imaging - John, Robin; Shinde, Dhanraj B.; Liu, Lili; Ding, Feng; Xu, Zhiping; Vijayan, Cherianath; Pillai, Vijayamohanan K.; Pradeep, Thalappil (ACS Nano, 2014)
We report an in situ Raman spectroscopic and microscopic investigation of the electrochemical unzipping of single-walled carbon nanotubes (SWNTs). Observations of the radial breathing modes (RBMs) using Raman spectral mapping reveal that metallic SWNTs are opened up rapidly followed by gradual unzipping of semiconducting SWNTs. Consideration of the resonant Raman scattering theory suggests that two metallic SWNTs with chiralities (10,4) and (12, 0) get unzipped first at a lower electrode potential (036 V) followed by the gradual unzipping of another two metallic tubes, (9, 3) and (10, 1), at a relatively higher potential (1.16 V). The semiconducting SWNTs with chiralities (11, 7) and (12, 5), however, get open up gradually at +/- 1.66 V. A rapid decrease followed by a subsequent gradual decrease in the metallicity of the SWNT ensemble as revealed from a remarkable variation of the peak width of the G band complies well with the variations of RBM. Cyclic voltammetry also gives direct evidence for unzipping in terms of improved capacitance after oxidation followed by more important removal of oxygen functionalities during the reduction step, as reflected in subtle changes of the morphology confirming the formation of graphene nanoribbons. The density functional-based tight binding calculations show additional dependence of chirality and diameter of nanotubes on the epoxide binding energies, which is in agreement with the Raman spectroscopic results and suggests a possible mechanism of unzipping determined by combined effects of the structural characteristics of SWNTs and applied field.
Keywords: density functional-based tight binding calculations; Electrochemistry; graphene; Raman spectral mapping; single-walled carbon nanotubes

Short enantioselective total synthesis of (R)- and (S)-pipecolic acid - Chavan, Subhash P.; Khairnar, Lalit B.; Chavan, Prakash N.; Kalbhor, Dinesh B. (Tetrahedron-Asymmetry, 2014)
A convenient and practical total synthesis of (R)- and (S)-pipecolic acid has been achieved by utilizing chiral cis-aziridine-2-carboxylate as the common synthetic precursor. The synthesis involves regioselective reductive cleavage of the aziridine ring and Wittig olefination as key reactions. (C) 2014 Elsevier Ltd. All rights reserved.

Silica and zirconia supported tungsten, molybdenum and gallium oxide catalysts for the synthesis of furfural - Bhaumik, Prasenjit; Kane, Tanushree; Dhepe, Paresh Laxmikant (Catalysis Science & Technology, 2014)
SiO2 and ZrO2 supported W, Mo and Ga oxide catalysts were prepared by a sol-gel and wet-impregnation method. The 10 wt% WO3/SiO2 (sol-gel) catalyst showed 61 +/- 2% furfural yield from hemicellulose in a one-pot fashion for at least 8 cycles. Based on XRD, TPD and Hammett acidity characterizations, the catalyst structure-activity correlation was drawn.

Simple and efficient synthesis of isocoumarins and alkylidenephthalides from 3-(1-hydroxycarbethoxy/alkyl)phthalides with a DEAD/PPh3/TBHP system - Gadakh, Sunita K.; Sudalai, Arumugam (RSC Advances, 2014)
A facile and novel approach to the synthesis of 3-carbethoxy-isocoumarins and 3-alkylidenephthalides is described. The methodology employs DEAD/PPh3/TBHP as the reagent system proceeding through unprecedented 1,2-shift intramolecular ring expansion or simple elimination depending upon substituents present on 3-substituted phthalides, with broader substrate scope. This strategy is amply demonstrated in the short synthesis of bioactive molecules such as cytogenin and (Z)-3-butylidene-7-hydroxy-5-methoxyphthalide.

Simple, economical, and environmentally benign protocol for the synthesis of 2-amino-3,5-dicarbonitrile-6-sulfanylpyridines at ambient temperature - Desai, Uday V.; Kulkarni, Makarand A.; Pandit, Kapil S.; Kulkarni, Aparna M.; Wadgaonkar, Prakash P. (Green Chemistry Letters and Reviews, 2014)
A simple, economical, and environmentally benign protocol has been described for one-pot synthesis of medicinally privileged 2-amino-3,5-dicarbonitrile-6-sulfanylpyridines by three-component condensation between aldehyde, malononitrile, and thiol using diethylamine as a catalyst. Ambient temperature and avoidance of conventional work-up as well as purification procedure qualify this cost-effective protocol for ``green synthesis.''
Keywords: 5-dicarbonitriles; diethylamine; green chemistry; multicomponent reactions; organocatalyst; pyridine-3

Simple molecular engineering of glycol nucleic acid: progression from self-pairing to cross-pairing with cDNA and RNA - Bose, Tanaya; Kumar, Vaijayanti A. (Bioorganic & Medicinal Chemistry, 2014)
The acyclic chiral nucleic acid analogue, Glycol Nucleic Acid (GNA), displayed exceptional structural simplicity and atom economy while forming self-paired duplexes, using canonical Watson-Crick base pairing. We disclose here that the replacement of phosphodiester linker in GNA with somewhat rigid and shorter carbamate linker in Glycol Carbamate Nucleic Acid (GCNA) backbone allows unprecedented stability to the antiparallel self-paired duplexes. The R-GCNA oligomers were further found to form cross-paired antiparallel duplexes with cDNA and RNA following Watson-Crick base pairing. The stability of cross-paired GCNA: DNA and GCNA: RNA duplexes was higher than the corresponding DNA: DNA and DNA: RNA duplexes. The chiral (R) and (S) precursors were easily accessible from naturally occurring L-serine. (C) 2014 Elsevier Ltd. All rights reserved.
Keywords: Acyclic chiral nucleic acid; Cross-pairing; GCNA; GNA; Self-pairing

Single-layer MoSe2 based NH3 gas sensor - Late, Dattatray J.; Doneux, Thomas; Bougouma, Moussa (Applied Physics Letters, 2014)
High performance chemical sensor is highly desirable to detect traces of toxic gas molecules. Two dimensional (2D) transition metal dichalcogenides (TMDC) semiconducting materials has attracted as high performance gas sensor device applications due to unique properties such as high surface to volume ratio. Here, we describe the utilization of single-layer MoSe2 as high-performance room temperature NH3 gas sensors. Our single-layer MoSe2 based gas sensor device shows comprehensible detection of NH3 gas down to 50 ppm. We also confirmed gas sensing measurement by recording the Raman spectra before and after exposing the device to NH3 gas, which subsequently shows the shift due to charger transfer and analyte gas molecule adsorption on surface of single-layer MoSe2 nanosheet. Our investigations show the potential use of single-layer and few layer thick MoSe2 and other TMDC as high-performance gas sensors. (C) 2014 AIP Publishing LLC.

Single-pot formation of THFAL via catalytic hydrogenation of FFR over Pd/MFI catalyst - Biradar, Narayan S.; Hengne, Amol M.; Birajdar, Shobha N.; Niphadkar, Prashant S.; Joshi, Praphulla N.; Rode, Chandrashekhar V. (ACS Sustainable Chemistry & Engineering, 2014)
Furfural (FFR) was selectively hydrogenated in a single pot to tetrahydrofurfuryl alcohol (THFAL) over a Si MFI molecular sieve supported Pd catalyst. Studies on catalyst screening revealed that both the metal function and the support were critical for directing the selectivity to the ringhydrogenated product, THFAL. The structural feature of MFI as shown by XRD was completely retained in the used sample of the 3% Pd/MFI catalyst confirming its stability under reaction conditions. XRD, along with SEM characterization of the used samples, established retention of morphology of the structured silicate, suggesting a strong interaction between hexagonal porous silicate and Pd particles. The complete conversion of FFR with an enhanced selectivity of 95% to THFAL could be achieved by recycling the crude of the first hydrogenation experiment over the same 3% Pd/MFI catalyst.
Keywords: Biomass conversion; Hydrogenation; Pd/MFI; Recyclability; THFAL

Size quantization effects on interfacial electron transfer dynamics in Ru(II)-polypyridyl complex sensitized ZnO QDs - Verma, Sandeep; Das, Amitava; Ghosh, Hirendra N. (Journal of Physical Chemistry C, 2014)
Quantum-size confinement in semiconductor material offers size based tunability of interband gap energy as well as intraband sublevels. In this work, size quantization of wide bandgap ZnO quantum dots has been explored in the study of interfacial charge separation reaction using a catechol functionalized Ru(II)polypyridyl complex as a photosensitizer molecule. Femtosecond time-resolved transient absorption studies have revealed multiple electron injection events based on discrete conduction band states of ZnO QDs. The electron injection rates have been rationalized for quantum confinement effects owing to different sizes of ZnO QDs. Furthermore, the size dependency of the intrinsic lifetime of electrons injected into discrete energy levels of ZnO QDs has been revealed in charge recombination reaction with the Ru(III)polypyridyl complex cation. The charge recombination dynamics reveals a competing trend of carrier confinement and carrier leak upon reducing particle size. This study shows the optimization of finite size effects in achieving better interfacial charge separation at the dye/semiconductor interface.

Smallest organocatalyst in highly enantioselective direct aldol reaction in wet solvent-free conditions - Bhowmick, Sudipto; Kunte, Sunita S.; Bhowmick, Kartick C. (RSC Advances, 2014)
The catalytic efficacy of the smallest organocatalyst, L-proline hydrazide, prepared from a cheaply available natural amino acid, such as L-proline, was studied for the direct asymmetric aldol reaction of various ketones with aromatic aldehydes at room temperature in the presence of several acid additives. A loading of 10 mol% of catalyst 1 and p-toluenesulphonic acid as an additive was employed in this reaction, and good yields (up to 99%) with high anti/syn diastereoselectivities (up to 95 : 5) and enantioselectivities (up to >99.9%) were achieved in aqueous media.

Soft colloidal scaffolds capable of elastic recovery after large compressive strains - Rajamanickam, Raja; Kumar, Sushma; Kumar, Deepak; Ghosh, Shankar; Kim, Jong Chul; Tae, Giyoong; Sen Gupta, Sayam; Kumaraswamy, Guruswamy (Chemistry of Materials, 2014)
Assemblies of inorganic or glassy particles are typically brittle and cannot sustain even moderate deformations. This restricts the use of such materials to applications where they do not experience significant loading or deformation. Here, we demonstrate a general strategy to create centimeter-size macroporous monoliths, composed primarily (>90 wt %) of colloidal particles, that recover elastically after compression to about one-tenth their original size. We employ ice templating of an aqueous dispersion of particles, polymer, and cross-linker such that cross-linking happens in the frozen state. This method yields elastic composite scaffolds for starting materials ranging from nanoparticles to micron-sized dispersions of inorganics or glassy lattices. The mechanical response of the monoliths is also qualitatively independent of polymer type, molecular weight, and even cross-linking chemistry. Our results suggest that the monolith mechanical properties arise from the formation of a unique hybrid microstructure, generated by cross-linking the polymer during ice templating. Particles that comprise the scaffold walls are connected by a cross-linked polymeric mesh. This microstructure results in soft monoliths, with moduli similar to O (10(4) Pa), despite the very high particle content in their walls. A remarkable consequence of this microstructure is that the monolith mechanical response is entropic in origin: the modulus of these scaffolds increases with temperature over a range of 140 K. We show that interparticle connections formed by cross-linking during ice templating determine the monolith modulus and also allow relative motion between connected particles, resulting in entropic elasticity.

Soft-sensor development for biochemical systems using genetic programming - Sharma, Suraj; Tambe, Sanjeev S. (Biochemical Engineering Journal, 2014)
Soft-sensors are software based process monitoring systems/models. In real-time they estimate those process variables, which are difficult to measure online or whose measurement by analytical procedures is tedious and time-consuming. In this study, the genetic programming (GP), an artificial intelligence based data-driven modeling formalism, has been introduced for the development of soft-sensors for biochemical processes. The novelty of the GP is that given example input-output data, it searches and optimizes both the form (structure) and parameters of an appropriate linear/nonlinear data-fitting model. In this study, GP-based soft-sensors have been developed for two bioprocesses, namely extracellular production of lipase enzyme and bacterial production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer. While in case study-I, the soft-sensor predicts the time-dependent lipase activity (U/ml), in case study-II it predicts the amount of accumulated polyhydroxyalkanoates (% dcw). The prediction and generalization performance of the GP-based soft-sensors was compared with the corresponding multi-layer perceptron (MLP) neural network and support vector regression (SVR) based soft-sensors. This comparison indicates that in the first case study the GP-based soft-sensor with the training and test set correlation coefficient (root-mean-squared-error) magnitudes of >0.96 (approximate to 0.962 U/ml) has clearly outperformed the two other soft-sensors. In case study-II involving bacterial copolymer production, the GP and SVR based soft-sensors have performed equally well (correlation coefficient approximate to 0.98) while the MLP based soft-sensor's performance was relatively inferior (correlation coefficient approximate to 0.94). (C) 2014 Elsevier B.V. All rights reserved.
Keywords: Artificial intelligence; Batch processing; Bioprocess monitoring; Lipase; Modeling; sensors

Solar photocatalytic degradation of methylene blue using doped TiO2 nanoparticles - Bhosale, R. R.; Pujari, S. R.; Muley, G. G.; Patil, S. H.; Patil, K. R.; Shaikh, M. F.; Gambhire, A. B. (Solar Energy, 2014)
Doped-TiO2 nanoparticles (M:TiO2: Fe, Zn, Zr, Sb, Ce and nM:TiO2: B, C, N, P, S) with anatase structure were prepared by sol-gel method and characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), Brunauer-Teller method (BET), UV-Vis diffuses reflectance spectroscopy (DRS). Results revealed that the anatase structure is highly stable for all doped TiO2 prepared compounds with enhancement in the surface area. UV-Vis diffuse reflectance spectra showed that these dopants were responsible for narrowing the band gap of TiO2 and shifting its optical response from ultraviolet to visible-light region. The photocatalytic activities of these multi-doped TiO2 catalysts were investigated by degradation methylene blue in aqueous solution under solar-light illumination. The results showed an appreciable enhancement in the photoactivity of the C-doped TiO2 as compared to other multi-doped TiO2 because of the formation of Ti+3 species which prevent the recombination of electron-hole pairs in C-doped TiO2. (C) 2014 Elsevier Ltd. All rights reserved.
Keywords: Carbon; iron; Methylene blue; Solar photocatalysis

Sol-gel assisted fabrication of collagen hydrolysate composite scaffold: a novel therapeutic alternative to the traditional collagen scaffold - Ramadass, Satiesh Kumar; Perumal, Sathiamurthi; Gopinath, Arun; Nisal, Anuya; Subramanian, Saravanan; Madhan, Balaraman (ACS Applied Materials & Interfaces, 2014)
Collagen is one of the most widely used biomaterial for various biomedical applications. In this Research Article, we present a novel approach of using collagen hydrolysate, smaller fragments of collagen, as an alternative to traditionally used collagen scaffold. Collagen hydrolysate composite scaffold (CHCS) was fabricated with sol-gel transition procedure using tetraethoxysilane as the silica precursor. CHCS exhibits porous morphology with pore sizes varying between 380 and 780 mu m. Incorporation of silica conferred CHCS with controlled biodegradation and better water uptake capacity. Notably, 3T3 fibroblast proliferation was seen to be significantly better under CHCS treatment when compared to treatment with collagen scaffold. Additionally, CHCS showed excellent antimicrobial activity against the wound pathogens Staphylococcus aureus, Bacillus subtilis, and Escherichia coli due to the inherited antimicrobial activity of collagen hydrolysate. In vivo wound healing experiments with full thickness excision wounds in rat model demonstrated that wounds treated with CHCS showed accelerated healing when compared to wounds treated with collagen scaffold. These findings indicate that the CHCS scaffold from collagen fragments would be an effective and affordable alternative to the traditionally used collagen structural biomaterials.
Keywords: collagen; collagen hydrolysate; scaffold; sol-gel; tissue engineering; wound Healing

Solid acid catalyzed depolymerization of lignin into value added aromatic monomers - Deepa, Ayillath K.; Dhepe, Paresh Laxmikant (RSC Advances, 2014)
Depolymerization of lignin to produce value-added aromatic monomers has attracted a lot of attention since these monomers can potentially be used as fuel additives (octane enhancers) and in turn can improve the prospects of cellulosic ethanol technology to become economically feasible. Here we show that solid acid catalysts could efficiently convert lignin into value added aromatic monomers with 60% yields and ca. 95% mass balance when depolymerization reactions were carried out at 250 degrees C for 30-120 minutes. We found that the reaction parameters have a remarkable effect on improving the yields.

Solid base supported metal catalysts for the oxidation and hydrogenation of sugars - Tathod, Anup; Kane, Tanushree; Sanil, E. S.; Dhepe, Paresh Laxmikant (Journal of Molecular Catalysis A-Chemical, 2014)
Pt impregnated on gamma-Al2O3 (acidic support) and hydrotalcite (basic support) catalysts were synthesized, characterized and used in the oxidation and hydrogenation reactions of C5 and C6 sugars. In the absence of homogeneous base, 83% yield for gluconic acid; an oxidation product of glucose can be achieved over Pt/hydrotalcite (HT) catalyst at 50 degrees C under atmospheric oxygen pressure. Similarly, 57% yield for xylonic acid, an oxidation product of xylose is also possible over Pt/HT catalyst. Hydrogenation of glucose conducted using Pt/gamma-Al2O3 + HT catalytic system showed 68% sugar alcohols (sorbitol + mannitol) formation. The 82% yield for C5 sugar alcohols (xylitol + arabitol) was obtained by subjecting xylose to hydrogenation over Pt/gamma-Al2O3 + HT at 60 degrees C. UV analysis helped to establish the fact that under alkaline conditions sugars prefer to remain in open chain form in the solution and thus exposes -CHO group which further undergoes oxidation and hydrogenation reactions to yield acids and alcohols. (c) 2013 Elsevier B.V. All rights reserved.
Keywords: Hydrogenation; Oxidation; Solid base; Sugars; Supported metal catalysts

Solid, double-metal cyanide catalysts for synthesis of hyperbranched polyesters and aliphatic polycarbonates - Sebastian, Joby; Darbha, Srinivas (Journal of Chemical Sciences, 2014)
Fe-Zn and Co-Zn double-metal cyanide (DMC) complexes exhibit highly efficient and selective catalytic activity for synthesis of hyperbranched polyesters (glycerol succinic acid (G-SA) and glycerol adipic acid (G-AA)) and aliphatic polycarbonates (via., alternative co-polymerization of cyclohexene oxide and CO2), respectively. The influence of method of preparation of DMC, in particular the mode of addition of reagents, on its physicochemical and catalytic properties was investigated. Co-Zn DMC was found highly selective for polycarbonate (than polyethers) formation. Catalysts prepared using tert-butanol and PEG-4000 as complexing and co-complexing agents, respectively, were found superior to those prepared without these agents. Apart from its role as a coordinating ligand, tert-butanol activated the Lewis acidic Zn2+ sites for reactions in polyester and polycarbonate formation. Hydrophobicity, micro-mesoporosity, acid strength and the amount of coordinated complexing agent are some of the crucial factors influenced the catalytic activity of DMC complexes.
21st National Symposium on Catalysis (CATSYMP), CSIR Indian Inst Chem Technol, Hyderabad, INDIA, FEB 11-13, 2013
Keywords: aliphatic polycarbonate; CO2 utilization; Double-metal cyanide complex; heterogeneous catalysis; hyperbranched polyester

Solid-state NMR investigations of a MgCl2 center dot 4(CH3)(2)CHCH2OH molecular adduct: a peculiar case of reversible equilibrium between two phases - Thushara, K. S.; Ajithkumar, Thalasseril G.; Rajamohanan, P. R.; Gopinath, Chinnakonda S. (Journal of Physical Chemistry A, 2014)
MgCl2 center dot xROH molecular adducts are extensively employed as a support material for Ziegler-Natta polyolefin catalysis. However, their structural properties are not well understood. Recently, we reported on the preparation of an isobutanol adduct, MgCl2 center dot 4(CH3)(2)CHCH2OH (MgiBuOH) (Dalton Trans. 2012, 41, 11311), which is very sensitive to the preparation conditions, such as the temperature and refluxing time. For the present study, the structural properties of MgiBuOH adducts prepared under different conditions have been investigated thoroughly by solid-state NMR and nonambient XRD. Formation of two phases has been confirmed, and in situ variable temperature solid-state NMR measurements confirm the coexistence of two phases as well as the oscillation from one to another phase. It is expected that such molecular adducts could have a significant role in organic transformation reactions due to an oscillating structural component. An understanding of phase oscillation with the Mg2+ ion as the central metal ion might shed some light toward understanding various biological and structural functions.

Solvothermal synthesis of mesoporous manganese oxide with enhanced catalytic activity for veratryl alcohol oxidation - Jha, Ajay; Chandole, Tejansh; Pandya, Rajan; Roh, Hyun-Seog; Rode, Chandrashekhar V. (RSC Advances, 2014)
Catalyst activities of manganese and cobalt oxides prepared by solvothermal and co-precipitation methods were studied for veratryl alcohol oxidation. Manganese oxides showed higher activity performance than that of cobalt oxides irrespective of the method of preparation. The solvothermal method yielded mesoporous manganese oxide without using any template giving mixed phases of monoclinic Mn5O8 and hausmannite Mn3O4. The mesoporous manganese oxide exhibited excellent activity for liquid phase aerobic oxidation of veratryl alcohol under base free conditions, with 90% conversion and almost complete selectivity towards veratraldehyde. The detailed characterization results on morphology, size and composition of the prepared mesoporous manganese oxide obtained by XRD, XPS, H-2-TPR, N-2 adsorption-desorption isotherms, FESEM and HR-TEM techniques were used to understand the role of morphological and structural features in enhancement of the observed catalytic activity.

Special issue section commemorating Prof. J. B. Joshi - Nandakumar, K.; Kulkarni, A. (Canadian Journal of Chemical Engineering, 2014)

Specific probe for Hg2+ to delineate even H+ in pure aqueous buffer/Hct116 colon cancer cells: Hg(II)-eta(2)-arene pi-interaction and a TBET-based fluorescence response - Reddy, Upendar G.; Ramu, Vadde; Roy, Sovan; Taye, Nandaraj; Chattopadhyay, Samit; Das, Amitava (Chemical Communications, 2014)
A new molecular probe that demonstrates a distinct TBET process, induced by the Hg(II)-eta(2)-arene pi-interaction, in pure aqueous medium with a large pseudo-Stokes shift of 200 nm.

Spectroscopic and antibacterial studies of new octaazamacrocyclic complexes derived from carbohydrazide and isatin - Kumar, Krishan; Kamboj, Monika; Jain, Kiran; Singh, D. P. (Spectrochimica Acta Part A-Molecular and Biomolecular Spectroscopy, 2014)
A novel series of the macrocyclic complexes of the type: [M(C18H14N10O2)X-2], where M = Co(II), Ni(II), Cu(II) and Zn(II); X = Cl-, NO3- and CH3COO-, has been synthesized by template condensation of carbohydrazide and isatin in methanolic medium. The complexes were characterized by various physico-chemical techniques, such as elemental analyses, molar conductance measurements, magnetic measurements, and electronic, NMR, IR and EPR spectral studies. The low value of molar conductance indicates them to be non-electrolytes. Based on various studies, a distorted octahedral geometry was proposed for all the metal complexes. Metal complexes were tested for their in vitro antibacterial activities against some pathogenic bacterial strains and compared with standard antibiotic, Ciprofloxacin. Some of the tested complexes was found effective against Gram-positive bacterial strains. (C) 2014 Elsevier B.V. All rights reserved.
Keywords: Carbohydrazide; Isatin; Macrocyclic complexes; MIC; Template condensation

Spontaneous jamming and unjamming in a hopper with multiple exit orifices - Kunte, Amit; Doshi, Pankaj; Orpe, Ashish V. (Physical Review E, 2014)
We show that the flow of granular material inside a two-dimensional flat bottomed hopper is altered significantly by having more than one exit orifice. For hoppers with small orifice widths, intermittent flow through one orifice enables the resumption of flow through the adjacent jammed orifice, thus displaying a sequence of jamming and unjamming events. Using discrete element simulations, we show that the total amount of granular material (i.e., avalanche size) emanating from all the orifices combined can be enhanced by about an order of magnitude difference by simply adjusting the interorifice distance. The unjamming is driven primarily by fluctuations alone when the interorifice distance is large, but when the orifices are brought close enough, the fluctuations along with the mean flow cause the flow to unjam.

Stable silanone with a three-coordinate silicon atom: a century-long wait is over - Sen, Sakya S. (Angewandte Chemie-International Edition, 2014)
Keywords: cations; germanones; Ketones; silanones; transition metals

Static and dynamic photoluminescence and photocatalytic properties of uniform, monodispersed up/down-converting, highly luminescent, lanthanide-ion-doped beta-NaYF4 phosphor microcrystals with controlled multiform morphologies - Padhye, Preeti; Poddar, Pankaj (Journal of Materials Chemistry A, 2014)
Lanthanide-ion-doped, single-crystalline hexagonal phase NaYF4 microcrystals with multiform morphologies, such as microrods, hexagonal microprisms, and spindle-like structures, were fabricated via a cationic/anionic binary capping agent system: CTAB and a tri-sodium citrate-assisted hydrothermal route. The influence of synthesis conditions on the crystalline morphology was studied and the possible growth mechanisms are presented systematically. The down-conversion and up-conversion photoluminescence (PL) properties of beta-NaYF4:Ln(3+) (Ln = Tb, Yb/Er, and Yb/Tm) were investigated. The static and dynamic PL studies of beta-NaYF4:5% Tb3+ showed strong dependence of luminescent properties on the crystalline morphology. Furthermore, the beta-NaYF4:5% Tb3+ phosphors exhibited efficient photocatalytic activity under UV as well as solar light irradiation, and showed enhanced selectivity towards methylene blue. Moreover, the morphological effect on the photocatalytic activity of beta-NaYF4:5% Tb3+ crystals has also been studied. The high luminescence efficiency and strong photocatalytic activity of beta-NaYF4:5% Tb3+ make them a potential phosphor material and promise to provide a gateway into other applications as in biology and materials sciences.

Status of membrane distillation for water and wastewater treatment-a review - Pangarkar, Bhausaheb L.; Sane, Mukund G.; Parjane, Saroj B.; Guddad, Mahendra (Desalination and Water Treatment, 2014)
Membrane distillation (MD) is a promising separation technique for water treatment. It is a nonisothermal process known since 1963. However, this technology still needs to be developed for its industrial implementation for different purposes. This paper presents a status review of MD based on the available published literatures and on preliminary analysis. The review covers the concept, membranes and modules design, configurations, performance parameters, fouling phenomena, the heat and mass transfer phenomena, applications, energy assessment, heat integration, and Memstill technology of MD process. Earlier study indicates that the permeate quality obtained by MD is stable and practically independent on the feed concentrations. The permeate flux is strongly affected by the feed temperature, feed flow rate, vacuum pressure in vacuum MD, and the boundary layer heat transfer coefficient. The permeate flux obtained in the literature of MD process is disagree by an order of enormity and hence better experimental work is needed. The less attention was found in the literature towards the removal of organic and inorganic toxic constituents from the groundwater by MD process.
Keywords: Fouling; Membrane configuration; Membrane design; Membrane distillation; wastewater

Steady state fluorescence studies of wild type recombinant cinnamoyl CoA reductase (Ll-CCRH1) and its active site mutants - Sonawane, Prashant; Vishwakarma, Rishi Kishore; Singh, Somesh; Gaikwad, Sushama M.; Khan, Bashir Mohammad (Journal of Fluorescence, 2014)
Fluorescence quenching and time resolved fluorescence studies of wild type recombinant cinnamoyl CoA reductase (Ll-CCRH1), a multitryptophan protein from Leucaena leucocephala and 10 different active site mutants were carried out to investigate tryptophan environment. The enzyme showed highest affinity for feruloyl CoA (K (a) = 3.72 x 10(5) M-1) over other CoA esters and cinnamaldehydes, as determined by fluorescence spectroscopy. Quenching of the fluorescence by acrylamide for wild type and active site mutants was collisional with almost 100 % of the tryptophan fluorescence accessible under native condition and remained same after denaturation of protein with 6 M GdnHCl. In wild type Ll-CCRH1, the extent of quenching achieved with iodide (f (a) = 1.0) was significantly higher than cesium ions (f (a) = 0.33) suggesting more density of positive charge around surface of trp conformers under native conditions. Denaturation of wild type protein with 6 M GdnHCl led to significant increase in the quenching with cesium (f (a) = 0.54), whereas quenching with iodide ion was decreased (f (a) = 0.78), indicating reorientation of charge density around trp from positive to negative and heterogeneity in trp environment. The Stern-Volmer plots for wild type and mutants Ll-CCRH1 under native and denatured conditions, with cesium ion yielded biphasic quenching profiles. The extent of quenching for cesium and iodide ions under native and denatured conditions observed in active site mutants was significantly different from wild type Ll-CCRH1 under the same conditions. Thus, single substitution type mutations of active site residues showed heterogeneity in tryptophan microenvironment and differential degree of conformation of protein under native or denatured conditions.
Keywords: Active site mutants; Cinnamoyl CoA reductase; fluorescence; Ligand binding; Solute quenching

Stereoselective approach to 2,6-disubstituted piperidin-3-ol: synthesis of (-)-deoxoprosopinine and (+)-deoxoprosophylline - Jha, Vishwajeet; Kauloorkar, Shruti Vandana; Kumar, Pradeep (European Journal of Organic Chemistry, 2014)
A simple and highly efficient approach to an enantioenriched 2,6-disubstituted piperidin-3-ol skeleton is developed from an aldehyde as a starting material by using organocatalytic and asymmetric dihydroxylation as the key steps. Its application to the total synthesis of (-)-deoxoprosopinine and (+)-deoxoprosophylline is also reported.
Keywords: alkaloids; Amination; Amino alcohols; synthetic methods; Wittig reactions

Stereoselective approach to indolizidine and pyrrolizidine alkaloids: total synthesis of (-)-lentiginosine, (-)-epi-lentiginosine and (-)-dihydroxypyrrolizidine - Kauloorkar, Shruti Vandana; Jha, Vishwajeet; Jogdand, Ganesh F.; Kumar, Pradeep (Organic & Biomolecular Chemistry, 2014)
A simple and highly efficient approach to hydroxylated pyrrolizidine and indolizidine is developed from an aldehyde as a starting material using organocatalytic and asymmetric dihydroxylation reactions as key steps. Its application to the total synthesis of (-)-lentiginosine, (-)-epi-1,2-lentiginosine and (-)-dihydroxypyrrolizidine is also reported.

Stereospecific synthetic approach towards tamiflu using the ramberg-backlund reaction from cysteine hydrochloride - Chavan, Subhash P.; Chavan, Prakash N.; Gonnade, Rajesh G. (RSC Advances, 2014)
The stereospecific formal synthesis of Tamiflu from L-cysteine hydrochloride as the chiral source is described. The notable feature of the present strategy is the Ramberg-Backlund reaction and Sharpless-Reich protocol as the key chemical transformations to access the cyclohexene skeleton of Tamiflu.

Stress inducible proteomic changes in capsicum annuum leaves - Mahajan, Neha S.; Mishra, Manasi; Tamhane, Vaijayanti A.; Gupta, Vidya S.; Giri, Ashok P. (Plant Physiology and Biochemistry, 2014)
Herbivore attack induces defense responses in plants, activating several signaling cascades. As a result, molecules deterrent to the herbivores are produced and accumulated in plants. Expression of defense mechanism/traits requires reorganization of the plant metabolism, redirecting the resources otherwise meant for growth. In the present work, protein profile of Capsicum annuum leaves was examined after herbivore attack/induction. Majority of proteins identified as differentially accumulated, were having roles in redox metabolism and photosynthesis. For example, superoxide dismutase and NADP oxidoreductase were upregulated by 10- and 6-fold while carbonic anhydrase and fructose-1,6-bisphosphatase were downregulated by 9- and 4-fold, respectively. Also, superoxide dismutase, NADPH quinone oxidoreductase and NADP dependent isocitrate dehydrogenase transcripts showed a higher accumulation in induced leaf tissues at early time points. In general, proteins having role in defense and damage repair were upregulated while those involved in photosynthesis appeared downregulated. Thus metabolic reconfiguration to balance defense and tolerance was evident in the stress-induced leaves. (C) 2013 Elsevier Masson SAS. All rights reserved.
Keywords: Capsicum annuum; Oxidative stress; Wounding

Structural basis of Iridoid synthase mediated cyclization of 10-oxogeranial - Sandholu, Anandsukeerthi; H. V. Thulasiram; Sengupta, Jayati; Kulkarni, Kiran (Acta Crystallographica A‐Foundation and Advances, 2014)
Keywords: Cryo-EM; iridoid synthase; Single Particle reconstruction

Structural characterization of a UbiA superfamily member of archaeal origin - Boral, Debjyoti; Ramasamy, Suresh Kumar (Acta Crystallographica A‐Foundation and Advances, 2014)
Keywords: Lipid biosynthesis; UbiA superfamily

Structural diversity in serine derived homochiral metal organic frameworks - Kundu, Tanay; Banerjee, Rahul (Journal of Chemical Sciences, 2014)
Two new Zn(II) and Cd(II) based homochiral metal-organic frameworks (MOFs) [SerCdOAc and Zn(Ser)(2)] have been synthesized using pyridyl functionalized amino acid, viz., serine, as an organic linker. The SerCdOAc structure is three dimensional, while that of the Zn(Ser)(2) is two dimensional. The polar voids of the corresponding MOFs are filled with solvent molecules (water in the case of SerCdOAc and methanol in the case of Zn(Ser)(2)). In both cases, metal centres, i.e., Zn(II) and Cd(II), are hexacoordinated. However, with a change in the solvent for synthesis, ligand coordination mode and incorporation of additional coordinated anion resulted in a great change in the final MOF architecture. Herein, for the first time, we could achieve structural variety and synthesize MOFs composed of only metal ion and pyridyl functionalized amino acid linker.
Keywords: Amino acid; crystal engineering; hydrogen bonding; metal organic framework

Structural investigations of porous MgCl2-2-butanol molecular adduct as support for olefin polymerization - Thushara, K. S.; Ajithkumar, Thalasseril G.; Rajamohanan, P. R.; Gopinath, Chinnakonda S. (Applied Catalysis A-General, 2014)
A new heterogeneous Ziegler-Natta (Z-N) catalyst support material, MgCl2 center dot 4(CH3CH(OH)CH2CH3) (Mg2BuOH) has been synthesized. 2-Butanol, a linear, secondary alcohol was chosen for the generation of an active MgCl2 support which results in a Z-N catalyst with TiCl4. Significant feature of this work is the formation of rod shaped molecular adduct with highly porous character. Adduct material is characterized by XRD, TG-DTA, Raman spectroscopy, solid-state NMR and SEM. Activity of the Z-N catalyst supported on Mg2BuOH for ethylene polymerization is comparable with that of commercially available heterogeneous Z-N catalyst. However, there is scope to improve the activity by optimizing textural properties. (C) 2013 Elsevier B.V. All rights reserved.
Keywords: heterogeneous catalysis; MgCl2; Molecular adduct; NMR; Polyolefin; Ziegler-Natta catalyst

Structural studies on an atypical Rho GTPase RhoH - Motiwala, Zenia; Kulkarni, Kiran (Acta Crystallographica A‐Foundation and Advances, 2014)
Keywords: lymphoma; RhoH; TCR signalling

Structure and dynamics of benzyl-NX3 (X = Me, Et) trifluoromethanesulfonate ionic liquids - Sunda, Anurag Prakash; Dhavale, Vishal M.; Kurungot, Sreekumar; Venkatnathan, Arun (Journal of Physical Chemistry B, 2014)
Ammonium-based benzyl-NX3 (X = methyl, ethyl) trifluoromethanesulfonate (TFA) ionic liquids (ILs) are low cost, nontoxic, thermally stable ion-conducting electrolytes in fuel cells and batteries. In the present study, we have characterized the structure and dynamics of these ILs using molecular dynamics (MD) simulations and ionic conductivity using electro-chemical impedance spectroscopy (EIS) at varying temperature and relative humidity (RH). Results from MD simulations predict that cation-cation and cation-anion interactions are stronger in benzyltrimethylammonium (BzTMA) compared to benzyltriethylammonium (BzTEA) that diminish with increase in RH. Further, the BzTMA cations show both C-H/Ph (center of mass of phenyl ring) and cation-Ph interactions whereas BzTEA cations show only strong cation-Ph interactions. The C-H/Ph interactions (psi >= 90 degrees, d(H-Ph) <= 4 angstrom, theta < 50 degrees and d(C.Ph) <= 4.3 angstrom) in BzTMA cations increase with RH and are highest at RH = 90%. The cumulative impact of electrostatic, cation/Ph, and C-H/Ph interactions results in lower conductivity of BzTMA-TFA IL compared to BzTEA-TFA IL. The EIS measurements show that the trends in ionic conductivity of ILs at RH = 30 and 90% are qualitatively similar to the Nernst-Einstein conductivity from MD simulations. The ionic conductivity of BzTEA-TFA IL is similar to 3 times higher than BzTMA-TFA IL at 353 K and RH = 90%.

Structure function attributes of gold nanoparticle vaccine association: effect of particle size and association temperature - Barhate, Ganesh A.; Gaikwad, Sushama M.; Jadhav, Suresh S.; Pokharkar, Varsha B. (International Journal of Pharmaceutics, 2014)
Many biotherapeutic applications of gold nanoparticles make use of conjugated or adsorbed protein moieties. Physical parameters of association such as particle size, morphology, surface chemistry and temperature influences the protein-nanoparticle association and thereby their interaction with the biological environment. In present study, effect of size of chitosan reduced gold nanoparticles (CsAuNPs) and association temperature on structure and function of tetanus toxoid (TT) vaccine has been investigated. CsAuNPs were synthesized in the sizes of 20 + 3, 40 + 5 and 80 + 7 nm followed by loading of TT. Binding process of CsAuNPs with TT was investigated at their predetermined micro molar concentrations. Upon binding of TT onto CsAuNPs, particle surface was characterized using X-ray photoelectron spectroscopy. CD spectroscopic evaluation of TT bound 20 nm CsAuNPs led to 75% reduction in secondary structure of TT and thereby compromised immune function. Binding of TT with 40 and 80 nm sized CsAuNPs did not cause significant modifications in secondary structure or function of TT. Thermodynamic studies using temperature dependent fluorescence spectroscopy revealed an increase in association constants with the temperature. Based on thermodynamic data three phases in CsAuNPs and TT association process were traced. Samples from these distinct phases were also investigated for immunological recognition. Ex-vivo interaction of TT-CsAuNPs with TT positive and negative sera followed by relative change in particle size and zeta potential was studied. The findings here suggests prominent role of particle size and association temperature on adsorbed TT structure and function. Such studies may help in engineering functional nanotherapeutics. (C) 2014 Elsevier B.V. All rights reserved.
Keywords: Association thermodynamics; Gold nanoparticle; Nanoparticle protein interaction; Structure function studies; Vaccine formulation

Structure of highly active BSH enzyme with subordinated post-translational excision - Chand, Deepak; Panigrahi, Priyabrata; Ramasamy, Sureshkumar; Suresh, C. G. (Acta Crystallographica A‐Foundation and Advances, 2014)
Keywords: Bile salt hydrolase; Mutagenesis; X-ray crystallography

Structure sensitive chemical reactivity by palladium concave nanocubes and nanoflowers synthesised by a seed mediated procedure in aqueous medium - Sreedhal, S.; Sudheeshkumar, V.; Vinod, C. P. (Nanoscale, 2014)
Palladium nanocubes and their transformation to concave nanocubes and nanoflowers are realised by a seed mediated procedure in aqueous medium and at room temperature using cationic surfactants. The concave nanocubes and nanoflowers were found to be enclosed by high index facets. The under coordinated atoms present on the high index facets make these nanostructures chemically more active towards Suzuki coupling and Heck coupling reactions compared to the conventional nanocubes and spherical nanoparticles of similar size.

Structure, stability, and properties of the trans peroxo nitrate radical: the importance of nondynamic correlation - Dutta, Achintya Kumar; Dar, Manzoor; Vaval, Nayana; Pal, Sourav (Journal of Physical Chemistry A, 2014)
We report a comparative single-reference and multireference coupled-cluster investigation on the structure, potential energy surface, and IR spectroscopic properties of the trans peroxo nitrate radical, one of the key intermediates in stratospheric NOx chemistry. The previous single-reference ab initio studies predicted an unbound structure for the trans peroxo nitrate radical. However, our Fock space multireference coupled-cluster calculation confirms a bound structure for the trans peroxo nitrate radical, in accordance with the experimental results reported earlier. Further, the analysis of the potential energy surface in FSMRCC method indicates a well-behaved minima, contrary to the shallow minima predicted by the single-reference coupled-cluster method. The harmonic force field analysis, of various possible isomers of peroxo nitrate also reveals that only the trans structure leads to the experimentally observed IR peak at 1840 cm(-1). The present study highlights the critical importance of nondynamic correlation in predicting the structure and properties of high-energy stratospheric NOx radicals.

Structure-property relationship in charge transporting behaviour of room temperature liquid crystalline perylenebisimides - Prajitha, K. P.; Chithiravel, Sundaresan; Krishnamoorthy, K.; Asha, S. K. (Journal of Materials Chemistry C, 2014)
A homologous series of pentadecyl phenol functionalized perylenebisimide (PBI) terminated with trialkoxy gallate esters was synthesized, where the terminal alkyl chain length was varied from n = 4 to 12 (PBI-En). The thermotropic liquid crystalline (LC) characteristics of the molecules were analyzed using differential scanning calorimetry (DSC), polarized light microscopy (PLM) combined with variable temperature wide angle X-ray diffraction (WXRD) techniques. A clear odd-even oscillation was observed in the melting as well as isotropization enthalpies as a function of alkyl spacer length in the terminal gallate unit, with the even spacers exhibiting higher values. The higher members of the series with n > 8 exhibited thermotropic liquid crystalline textures in the PLM, which remained stable until room temperature. The nature of the LC phase was identified to be columnar rectangular and columnar hexagonal based on detailed analysis of the WXRD pattern recorded in the LC phase. The WXRD pattern of the room temperature LC frozen samples indicated a nearly constant intra columnar stack distance of similar to 3.7 angstrom for all the members. The space-charge-limited current (SCLC) values of the LC frozen sample films were analyzed for dependence of the bulk mobility estimate on the nature of the LC phase. The columnar hexagonal phase exhibited a mobility value one order (10(-3) cm(2) V-1 s(-1)) higher than that of crystalline (10(-4) cm(2) V-1 s(-1)) and two orders higher than that of columnar rectangular phase (10(-5) cm(2) V-1 s(-1)), indicating a strong dependence of packing on bulk mobility.

Studies on morphology of polyaniline films formed at liquid-liquid and solid-liquid interfaces at 25 and 5 A degrees C, respectively, and effect of doping - Waghmode, Babasaheb J.; Patil, Sagar H.; Jahagirdar, Mandar M.; Patil, Virendra S.; Waichal, Rupali P.; Malkhede, Dipalee D.; Sathaye, Shivaram D.; Patil, Kashinath R. (Colloid and Polymer Science, 2014)
It is well accepted that the morphology of the nanomaterials has great effect on the properties and hence their applications. Therefore, morphology of materials has become a focus of research in the scientific world. The present study shows that interfacial polymerization and subsequent self-assembly provides a control over the morphology, nanorod/nanosheet, of polyaniline (PANI) films synthesized by liquid-liquid interface reaction technique and solid-liquid interface reaction technique. The synthesized PANI films and its particulate structure are characterized by using various spectroscopic techniques such as UV-visible, ATR-IR, Raman and XPS. The study confirmed the formation, the structure, the size and shape of particles and morphology of PANI by using analytical techniques namely, SAED, SEM and TEM. An important observation is that doping with HCl significantly improves the nanorod formation at the interface. The doped PANI electrode exhibits a higher area with rectangular shape in CV cycle and better cycle stability when compared with the performance of undoped PANI films. We believe that the results of these studies can give valuable leads to manoeuvre formation of PANI films with desired morphology for various applications.
Keywords: interfacial polymerization; Liquid-liquid interface; Nanorods; nanosheets; polyaniline; Self-assembly; Solid-liquid interface; Thin films

Studies on the effect of sintering conditions on the magnetostriction characteristics of cobalt ferrite derived from nanocrystalline powders - Mohaideen, Kamal Khaja; Joy, Pattayil Alias (Journal of the European Ceramic Society, 2014)
The effect of sintering conditions on the magnetostriction characteristics of sintered cobalt ferrite derived from nanocrystalline powders is studied. It is observed that the magnetostriction coefficient as well as the slope of the magnetostriction as a function of field depends on the microstructure of the sintered product. There is a direct correlation between the magnetostriction characteristics and density as well as porosity of the sintered products. Intragranular pores are found to be strongly influencing the magnetostriction characteristics. Similarly, correlation is found between the magnetostriction parameters and the Curie temperature, indicating the role of cation distribution which affects the magnetic anisotropy. Sintering the compacts made from nanocrystalline powders at 1450 degrees C for a very short duration is found to give high values of magnetostriction coefficient. However, higher values of magnetostriction at low magnetic fields are obtained for samples sintered at lower temperatures for longer duration and having relatively lower density. (C) 2013 Elsevier Ltd. All rights reserved.
Keywords: Cobalt ferrite; Magnetostriction; Microstructure; Nanocrystalline; Sintering

Study of base-catalyzed aldol reaction of trimethylsilyl enolates - Sutar, R. L.; Joshi, Navalkishore N. (Indian Journal of Chemistry Section B-Organic Chemistry Including Medicinal Chemistry, 2014)
Mukaiyama-type aldol reaction of trimethylsilyl enolates with aldehydes in the presence of a base is a complicated reaction. It usually results in various products determined by the nature of base and reaction medium. The present study has been undertaken to understand these factors and design new Lewis base catalysts to optimize the yield of desired aldol product. It has been shown that mild Bronsted base with inbuilt hydrogen bonding sites are efficient catalysts for the reactions involving trimethylsilyl enolates. Based on the observed results, a mechanism is proposed to explain the reaction outcome.
Keywords: Aldol reaction; base catalyzed; carboxylate salts; lithium amides

Subtilase from Beauveria sp.: conformational and functional investigation of unusual stability - Dalal, Sayli A.; More, Snehal V.; Shankar, Shiv; Laxman, Ryali Seeta; Gaikwad, Sushama M. (European Biophysics Journal With Biophysics Letters, 2014)
Retention of total activity of the subtilisin-like serine protease from Beauveria sp. MTCC 5184 (Bprot) in the vicinity of (1) 3 M GdnHCl for 12 h, (2) 50 % methanol and dimethyl sulfoxide each for 24 h, and (3) proteolytic enzymes (trypsin, chymotrypsin, and proteinase K) for 48 h led to expect the enzyme to be a kinetically stable protein. Also, the structure of the protein was stable at pH 2.0. Biophysical characterization and conformational transitions were monitored using steady-state and time-resolved fluorescence, FTIR, and CD spectroscopy. Single tryptophan in the protein exists as two conformers, in hydrophobic and polar environment. The secondary structure of Bprot was stable in 3 M GdnHCl as seen in far-UV CD spectra. The active fraction of Bprot obtained from size-exclusion chromatography in the presence of GdnHCl (1.0-3.0 M) eluted at reduced retention time. The peak area of inactive or denatured protein with the same retention time as that of native protein increased with increasing concentration of denaturant (1.0-4.0 M GdnHCl). However, the kinetics of GdnHCl-induced unfolding as studied from intrinsic fluorescence revealed k (unf) of native protein to be 5.407 x 10(-5) s(-1) and a half-life of 3.56 h. The enzyme is thermodynamically stable in spite of being resistant to the denaturant, which could be due to the effect of GdnHCl imparting rigidity to the active fraction and simultaneously unfolding the partially unfolded protein that exists in equilibrium with the folded active protein. Thermal and pH denaturation of Bprot exhibited interesting structural transitions.
Keywords: Beauveria; Chemical denaturation; Conformational transitions; Serine protease; Subtilase; Thermal denaturation; Thermodynamic stability

Sulfonic acid loaded self-standing covalent organic membrane for proton conduction - Sasmal, Himadri Sekhar; Banerjee, Rahul (Acta Crystallographica A‐Foundation and Advances, 2014)
Keywords: COF; Membrane; proton conduction

Superior grafting and state-of-the-art interfacial electron transfer rates for newly designed geminal dicarboxylate bound ruthenium(II)- and osmium(II)-polypyridyl dyes on TiO2 nanosurface - Banerjee, Tanmay; Biswas, Abul Kalam; Reddy, Upendar G.; Sahu, Tuhin Subhra; Das, Amitava; Ganguly, Bishwajit; Ghosh, Hirendra Nath (Journal of Physical Chemistry C, 2014)
Two new Ru(II)-/Os(II)-polypyridyl based sensitizer dyes with geminal dicarboxylic acid group as the binding unit for superior grafting of the dye to TiO2 have been designed and synthesized. Steady-state photochemical studies of the two sensitizer dyes in presence of TiO2 in water confirm strong binding of the dyes to TiO2. Femtosecond transient absorption studies of these newly synthesized dyes on TiO2 nanosurface have been carried out in water and the results have been compared with those for the corresponding 4,4'-dicarboxy-2,2'-bipyridine analogues of the dyes. While the charge recombination rates are considerably slower, interestingly, the electron injection rates are very fast for multiple saturated C-C linkages present between the chromophoric core and the anchoring moiety. The origin and the consequences of such profound effects on the ultrafast interfacial dynamics are discussed. This is the first report on the ultrafast transient absorption studies of dyes with geminal dicarboxylic acid binding groups, which we believe will add significantly to the present research efforts toward the development of robust and efficient dyes for use in dye solar applications.

Supramolecular gel to metal organic framework transformation - Chakraborty, Amit; Banerjee, Rahul (Acta Crystallographica A‐Foundation and Advances, 2014)
Keywords: gel; MOF; Supramolecular

Supramolecular P4VP-pentadecylphenol naphthatenebisimide comb-polymer: mesoscopic organization and charge transport properties - Narayan, Rekha; Kumar, Prashant; Narayan, K. S.; Asha, S. K. (Journal of Materials Chemistry C, 2014)
A supramolecular comb polymer of pentadecyl phenol (PDP) substituted naphthalenebisimide (PDP-UNBI) with poly(4-vinylpyridine) (P4VP) is reported. The mesoscopic organization within the P4VP(PDP-UNBI), complexes was studied using wide-angle X-ray diffraction (WXRD) technicjues. The packing diagram obtained from the single-crystal XRD analysis of the PDP-UNBI crystals gave a clear picture of the initial arrangement present in self-associated PDP-UNBI alone. Correlating this with the XRD data of the hydrogen-bonded polymer complex provided insight into the probable packing of the P4VP chains within the crystalline lattice of PDP-UNBI leading to a highly ordered lamellar packing. Transmission electron microscopy (TEM) revealed the uniform mesomorphic lamellar structures in the domain range of similar to 5-10 nm. Furthermore, the charge carrier mobility measurements observed from space-charge-limited current (SCLC) measurements demonstrated that transport behaviour of the hydrogen-bonded P4VP(PDP-UNBI) complex (2 x 10(-2) cm(2) V-1 s(-1)) was comparable to that of the crystalline naphthalenebisimide molecule itself (9 x 10(-3) cm(2) V-1 s(-1)), which is a great achievement, since the complex now offers a package of solution-processable n-type semiconductor polymer with mobility equivalent to that of a small crystalline molecule.

Supramolecular synthon hierarchy in bumetanide cocrystals - Allu, Suryanarayana; Bolla, Geetha; Tothadi, Srinu; Nangia, Ashwini (Acta Crystallographica A‐Foundation and Advances, 2014)
Keywords: Novel cocrystals of sulfonamide drug Bumetanide with carboxamides are developed based on supramolecular synthons approach

Supramolecular transitions in native cellulose-I during progressive oxidation reaction leading to quasi-spherical nanoparticles of 6-carboxycellulose - Sharma, Priyanka R.; Rajamohanan, Pattuparambil R.; Varma, Anjanikumar (Carbohydrate Polymers, 2014)
Cellulose-I swells considerably in phosphoric acid, and converts to amorphous cellulose via a cellulose-II transition state. Controlled oxidation of cellulose-I to 6-carboxycellulose (6CC) using HNO3-H3PO4-NaNO2 oxidation system led to the selective production of 6CC's of varying carboxyl contents (1.7-22%) as well as various shapes and sizes (macro-sized fibrils of several micron length and/or spherical nanoparticles of 25-35 nm), depending on the reaction conditions. 6CC's having less than 14% carboxyl content were largely in cellulose-II form (WAXRD values in-between cellulose I and cellulose II), whereas at 14-22% the 6CC's were largely amorphous; only trace crystallinity was observed at 19% and 22% carboxyl 6CC. Spherical nanoparticles retained a high degree of crystallinity having cellulose-I structure, whereas the macro-sized fibrils were largely converted to cellulose-II structure. Analysis by WAXRD as well as by CP-MAS C-13 NMR studies gave similar conclusions. Reduced molecular weight with progressive oxidation, including presence of oligomers, was also evident from an increase in the reducing-end carbon peak at similar to 92 ppm. For high oxidation levels (>14%) the NMR 92-96 ppm peaks disappeared on extracting with dilute alkali, due to soluble oligomers being removed. (C) 2014 Elsevier Ltd. All rights reserved.
Keywords: Carboxycellulose; cellulose; Nanoparticles; NMR; WAXRD

Surface studies on benzophenone doped PDMS microstructures fabricated using KrF excimer laser direct write lithography - Kant, Madhushree Bute; Shinde, Shashikant D.; Bodas, Dhananjay S.; Patil, K. R.; Sathe, V. G.; Adhi, K. P.; Gosavi, S. W. (Applied Surface Science, 2014)
his paper discusses microfabrication process for benzophenone doped polydimethylsiloxane (PDMS) using laser lithography. KrF excimer laser of 248 nm with 20 ns pulse width at repetition rate of 1 Hz was used for microfabrication of undoped and benzophenone doped PDMS. The doped-PDMS shows sensitivity below 365 nm, permitting processing under ambient light. The analysis of etch depth revealed that doped PDMS shows self developable sensitivity at lower fluence of similar to 250 mJ/cm(2). The unexposed and exposed surface was studied using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and Scanning electron microscopy (SEM). Spectrocopic analysis indicated increase in C-O, C=O, Si-O-3 and Si-O-4 bonding at the expense of Si-C and Si-O-2 bonds of PDMS. In case of laser exposed doped-PDMS, removal of benzophenone from probe depth of spectroscopy was observed. Whereas the surface morphology of exposed and unexposed doped-PDMS was observed to be same, indicating clean development of PDMS micropattems. The present study indicates that addition of 3.0 wt.% benzophenone in PDMS enhance self development sensitivity of PDMS. The self developable results on doped-PDMS are quite encouraging for its potential use in point of care Lab-On-Chip applications, for fabricating micropattems using direct write laser lithography technology.
Keywords: Direct write laser lithography; Microfabrication; micropatterning; Poly(dimethylsiloxane) (PDMS)

Surface synergism of an Ag-Ni/ZrO2 nanocomposite for the catalytic transfer hydrogenation of bio-derived platform molecules - Hengne, Amol M.; Malawadkar, Atul V.; Biradar, Narayan S.; Rode, Chandrashekhar V. (RSC Advances, 2014)
Levulinic acid was completely and selectively converted to GVL, in the presence of formic acid over an Ag-Ni/ZrO2 catalyst. The synergism between Ag and Ni in transfer hydrogenation eliminates the need for external hydrogen, making the process safer. The magnetic nature of the catalyst offers easy recovery for efficient recycling. This approach is standardized for the hydrogenation of several C-3-C-6 platform molecules in an aqueous medium.

Surfactant free gram scale synthesis of mesoporous Ni(OH)(2)-r-GO nanocomposite for high rate pseudocapacitor application - Singh, Upendra; Banerjee, Abhik; Mhamane, Dattakumar; Suryawanshi, Anil; Upadhyay, Kush Kumar; Ogale, Satishchandra (RSC Advances, 2014)
We report a single-step surfactant-free gram scale hydrothermal synthesis of mesoporous Ni(OH)(2) nanoparticles and the Ni(OH)(2)-reduced graphene oxide (Ni(OH)(2)-r-GO) nanocomposite. Interesting morphological features are noted. These nanomaterials are examined and compared as cathode materials for pseudo-capacitor application through detailed characterizations. A high specific capacitance (C-s) of 1538 F g(-1) is observed for Ni(OH)(2)-r-GO even at a high current density of 40 A g(-1), whereas at the same current rate, bare Ni(OH)(2) shows C-s of only 936 F g(-1).

Sustainable polyacetals from isohexides - Rajput, B. S.; Gaikwad, S. R.; Menon, Shamal K.; Chikkali, Samir H. (Green Chemistry, 2014)
A single step synthetic protocol to access a small family of renewable diacetals was established. The resultant chiral diacetals are valuable building blocks in pharmaceuticals and materials science. To demonstrate their synthetic competence, isohexide-diacetals (2a-c) were subjected to acetal metathesis polymerization and the corresponding polymers (poly2a-c) were isolated as white solids with molecular weights in the range 3200-27 600 (g mol(-1)). The semi-crystalline polymers displayed glass transition temperatures between 38-65 degrees C and melting temperatures in the range 103-156 degrees C. The isohexide derived polyacetats are stable under practical washing and rinsing conditions but degrade in slightly acidic media.

Syntheses, X-ray structures, catalytic activity and magnetic properties of two new coordination polymers of Co(II) and Ni(II) based on benzenedicarboxylate and linear N,N `-donor Schiff base linkers - Bhattacharya, Biswajit; Maity, Dilip Kumar; Pachfule, Pradip; Colacio, Enrique; Ghoshal, Debajyoti (Inorganic Chemistry Frontiers, 2014)
{Two isostructural coordination polymers based on Co(II) and Ni(II), {[M(azpy)(3)(p-bdc)(2)(H2O)(4)]center dot(CH3OH)(2)(H2O)(3)}(n) [where M = Co (1) and Ni (2); azpy = N,N'-bis-pyridin-4-ylmethylene-hydrazine and p-bdc = 1,4-benzenedicarboxylate], have been synthesized using mixed ligand systems at room temperature and characterized by single-crystal X-ray diffraction and other physicochemical methods. Structure determination reveals that both the complexes crystallize in the monoclinic space group C2/c and exhibit one-dimensional (1D) ladder like structures constructed by p-bdc and azpy ligands in which Schiff base (azpy) linkers serve as a bridging as well as pendent ligands. These pendent ligands are involved in H-bonding and pi-pi interactions with lattice water, methanol molecules and bridging azpy ligands, to form the 3D supramolecular structure. Notably, both the frameworks efficiently catalyze the Knoevenagel condensation reactions of a wide range of substituted benzaldehydes with active methylene compounds in heterogeneous medium under environmentally friendly conditions and the products were obtained in excellent yields. These catalysts were also found to exhibit excellent recyclability and re-usability without any significant loss of activity. A variable temperature magnetic study of both compounds was carried out and their magnetic properties justified on the basis of their crystal structure.

Synthesis and characterization of 3-[N,N `-bis-3-(salicylidenamino)ethyltriamine] Mo(VI)O-2@SBA-15: a highly stable and reusable catalyst for epoxidation and sulfoxidation reactions - Lazar, Anish; Thiel, Werner R.; Singh, A. P. (RSC Advances, 2014)
The efficient and reusable oxidation catalyst 3-[N,N'-bis-3-(salicylidenamino)ethyltriamine] Mo(VI)O-2@SBA-15 has been synthesized by the anchoring of the 3-[N,N-bis-3-(salicylidenamino)ethyltriamine] ligand (L or Salpr) on the inner surfaces of organofunctionalized SBA-15 and subsequent complexation with Mo(VI) O-2(acac)(2). The physico-chemical properties of the functionalized catalysts were analyzed by elemental analysis, ICP-OES, XRD, N-2-sorption measurements, TG & DTA, solid state C-13, Si-29 NMR spectroscopy, FT-IR, Raman spectroscopy, XPS, DRS UV-Vis spectroscopy, SEM and TEM. XRD and N-2 sorption analyses helped to find out the morphological and textural properties of the synthesized catalysts and confirm that an ordered mesoporous channel structure was retained even after the multistep synthetic procedures. The (100), (110) and (200) reflections in SBA-15 provide hints of a good structural stability, the existence of long range ordering and a high pore wall thickness. TG and DTA results reveal that the thermal stability of (L)Mo(VI)O-2@SBA-15 was maintained up to 300 degrees C. The organic moieties anchored over the surface of the SBA-15 support were determined by solid state C-13 NMR and FT-IR spectroscopy. Further, solid state Si-29 NMR spectroscopy provides the information about the degree of functionalization of the surface silanol groups with the organic moiety. The electronic environment and the oxidation state of the molybdenum site in (L)Mo(VI)O-2@SBA-15 were monitored by Raman spectroscopy, XPS and DRS UV-Vis techniques. Moreover, the morphology and topographic information of the synthesized catalysts were confirmed by SEM and TEM imaging. The synthesized catalysts were evaluated in epoxidation and sulfoxidation reactions, and the results show that (L)Mo(VI)O-2@SBA-15 exhibits high conversion and selectivity towards epoxidation and sulfoxidation reactions in combination with high stability. The anchored solid catalysts can be recycled effectively and reused several times without major loss in activity. In addition, Sheldon's hot filtration test was also carried out.

Synthesis and characterization of azoxy based mesogenic diols - Mulani, Khudbudin Baban; Ganjave, Nitin V.; Chavan, Nayaku (Indian Journal of Chemistry Section B-Organic Chemistry Including Medicinal Chemistry, 2014)
Azoxy based rigid mesogenic diols have been synthesized using two steps. Phenol/cresol is used as starting material. Synthesized diols are characterized by IR, H-1 and C-13 NMR, and mass spectroscopic methods. Thermal properties have been determined by thermo gravimetric analysis method and crystallinity patterns have been obtained by wide angle X-ray diffiactogram. Substituted phenol (methyl) is used to study the effect of substitution on physical and thermal properties of rigid azoxy mesogenic diol. The detailed characterization of azoxy based rigid diols is reported in this communication, which is highly useful for fundamental and applied research, particularly in liquid crystals and liquid crystalline polymers. The experimental results reveal that phenol based rigid mesogenic diols have high thermal stability and degree of crystallinity than methyl substituted rigid mesogenic diols.
Keywords: Azoxy; degree of crystallinity; diol; mesogen; phenol; thermal stability

Synthesis and characterization of hypercrosslinked hydroxyl functionalized co-polymer beads - Mane, Sachin; Ponrathnam, Surendra; Chavan, Nayaku (European Polymer Journal, 2014)
Hydroxyl functionalized beaded copolymers were synthesized from 2-hydroxy ethyl methacrylate by suspension polymerization using two different crosslinking agents (EDMA, DVB) and diluents (1,1,2,2-tetrachloroethane, 1,2-dichlorobenzene). Microporous beads with high surface area were successfully synthesized and characterized by different techniques. Maximum surface area obtained was 564 m(2)/g bearing uniform, spherical as well as non-aggregation images of beads. Thermal properties such as DTG and DSC reveal that, type of crosslinker (flexible/rigid) is major while its concentration is minor parameter that affect decomposition and softening temperature of copolymer. Swelling ratio of copolymer beads was examined as a function of crosslinker and crosslink density. Swelling behavior is in accordance with copolymer-solvent interaction parameter. (C) 2014 Elsevier Ltd. All rights reserved.
Keywords: Copolymer; Morphology; surface area; Suspension polymerization; Swelling ratio

Synthesis and characterization of triad based rigid mesogenic diols derived from hydroquinone and 4-hydroxybenzoic acid - Mulani, Khudbudin Baban; Ganjave, Nitin V.; Chavan, Nayaku (Indian Journal of Chemistry Section B-Organic Chemistry Including Medicinal Chemistry, 2014)
Triad based rigid mesogenic diols have been synthesized by four step synthesis method using protection-deprotection method. Hydroquinone and 4-hydroxy benzoic acid have been used as starting materials. Synthesized diols have been characterized by IR, H-1 and C-13 NMR, and mass spectroscopic methods. Thermal properties have been determined by thermo gravimetric analysis method and degree of crystallinity have been measured by wide angle X-ray technique. Substituted hydroquinones (methyl and chloro) have been used to study the effect of substitution on physical and thermal properties. Synthesis of rigid mesogenic diol monomer using p-hydroxy benzoic acid and hydroquinone is reported, which is a facile route. Hydrolysis of diacetate derivatives of rigid mesogenic diols is performed in good yields, even though two types of ester groups present in the same moiety, aromatic and aliphatic. The experimental results reveal that hydroquinone based rigid triad mesogenic diol have high thermal stability and degree of crystallinity as compared to methyl-and chloro-substituted rigid triad mesogenic diols.
Keywords: degree of crystallinity; ester hydrolysis; Mesogenic diols; spectral properties; Thermal properties

Synthesis and electrochemical performance of a single walled carbon nanohorn-Fe3O4 nanocomposite supercapacitor electrode (vol 3, pg 21390, 2013) - Deshmukh, Ashvini B.; Shelke, Manjusha V. (RSC Advances, 2014)

Synthesis and electrochemistry of pseudocapacitive multilayer fullerenes and MnO2 nanocomposites (vol 2, pg 2152, 2014) - Azhagan, Muniraj Vedi Kuyil; Vaishampayan, Mukta V.; Shelke, Manjusha V. (Journal of Materials Chemistry A, 2014)

Synthesis and electrochemistry of pseudocapacitive multilayer fullerenes and MnO2 nanocomposites - Azhagan, Muniraj Vedi Kuyil; Vaishampayan, Mukta V.; Shelke, Manjusha V. (Journal of Materials Chemistry A, 2014)
Electrode materials with efficient capabilities for ionic and electronic transport are key to high performance supercapacitors. Here, we demonstrate a simple and comparatively low temperature synthesis of functionalized multilayer fullerenes so called carbon nano-onions (CNOs) as the electrode for high performance electrochemical supercapacitors. The exohedral type supercapacitor formed due to nonporous CNOs showed higher specific capacitance than conventional graphitic/mesoporous/activated carbons. Surface redox functionalities of these CNOs add up to significant pseudocapacitance. Further in situ incorporation of MnO2 nanoparticles to these CNOs increased the specific capacitance up to 1207 F g(-1), which is close to the theoretical value of pseudocapacitive MnO2.

Synthesis and in situ observation of 3D super lattices of gold nanoparticles using oil-in-water emulsion - Dutta, Ankur; Chakraborty, Jayanta; Bhagavatula L. V. Prasad; Sahu, Puspanjali (Journal of Colloid and Interface Science, 2014)
In this work oil-in-water emulsion has been successfully used as a confined environment to grow 3D superlattices of gold nanoparticles. The superlattices were grown from 5 nm uniform gold nanoparticles using slow destabilization method. The confined environment was created by forming a stable emulsion where the gold colloid suspended in toluene was used as oil phase. Superlattices were also formed in bulk solution using the same slow destabilization method. A comparative study reveals that compact superlattices form more readily inside the emulsion drops as compared to bulk precipitation. The unstable colloid (in bulk or as emulsion) was aged for various periods at 5 degrees C to form more compact superlattices. The best superlattices with sharp corners are observed when the superlattices are formed inside the emulsion and aged for a month. Two key parameters, the incubation temperature and anti-solvent concentration, are optimized to obtain larger superlattices with sharp features. A new method is also demonstrated for in situ observation of superlattice formation using an optical microscope. 2014 Elsevier Inc. All rights reserved.
Keywords: 3D nanocrystal superlattices; In situ observation of superlattice formation; Monodisperse gold nanoparticles; Nanocrystal superlattices

Synthesis and luminescence of graphene-nano calcium sulphide composite - Sharma, Geeta; Patil, K. R.; Gosavi, S. W. (Materials Chemistry and Physics, 2014)
Graphene-nanocrystalline calcium sulphide has been synthesized using in-situ reduction of calcium salt and graphene oxide. Graphene oxide was prepared using Hummer's method. Surface morphology and crystal structure of samples were observed by transmission electron microscopy (TEM) and X-Ray diffraction (XRD). Ultra thin graphene and graphene oxide sheets with size ranging between tens to several hundreds of square nanometers are observed in TEM images. The TEM micrographs of G-CaS show that CaS particles are embedded in graphene sheets and the average particle size of CaS particles in the composite is less than 50 nm. The reduction in the intensity of various functional groups in FTIR spectrum also confirms the formation of graphene. The UV-Visible spectra of CaS shows absorption peak at 220 nm with a small shoulder at 250 nm whereas in G-CaS 220 nm absorption peak has reduced intensity and the shoulder at 250 nm has now shifted to 270 nm due to modification in the defect structure of CaS by graphene. CaS and G-CaS shows photoluminescence emission at 470 nm (lambda(exc.) = 375 nm) and 440 nm (lambda(exc.) = 350 nm) respectively, however emission intensity of G-CaS is relatively lower than CaS. Although the emission intensity is found to be lower than CaS, addition of CaS to graphene in G-CaS complex has made graphene luminescent. XPS spectra also indicate reduction of various oxygen containing functional groups in highly reduced graphene oxide and G-CaS. (C) 2014 Elsevier B.V. All rights reserved.
Keywords: Luminescence; Nanostructures; powder diffraction; Precipitation

Synthesis and reactivity of magnetically diverse Au@ Ni core-shell nanostructures - Bharathan, Vysakh A.; Raj, Govind K.; Joy, Pattayil Alias; Vinod, Chathakudath P. (Particle & Particle Systems Characterization, 2014)
Core-shell bimetallic Au@Ni nanoparticles, with gold cores and thin nickel shells with overall size less than 10 nm, are synthesized and stabilized in pure cubic (fcc) and hexagonal (hcp) phase. Due to their unique crystal, electronic, and geometric structure, they show interesting magnetic and chemical properties. The Au@Ni-fcc is magnetic, whereas Au@Ni-hcp is non-magnetic. Both the bimetallic nanostructures are stable to surface oxidation until 150 degrees C and show excellent catalytic activity for p-nitrophenol reduction reaction.
Keywords: Au-Ni nanoparticles; bimetallic nanostructures; magnetic core-shell nanoparticles; oxidation resistance

Synthesis, characterization, and crystal structure determination of palladacycles of para-substituted 2-thiobenzylazobenzenes - Bhattacharjee, Tirtha; Kalita, Mukul; Chakravarty, Debamitra K.; Barman, Pranjit; Puranik, Vedavati G. (Journal of Coordination Chemistry, 2014)
Bichelated neutral palladacycles (1-3), [Pd(L)Cl], were synthesized from reaction of the new potential tridentate (C,N,S) ligands, 2-thiobenzylazobenzene (L-1), 4'-methyl-2-thiobenzylazobenzene (L-2), and 4'-chloro-2-thiobenzylazobenzene (L-3) with sodium tetrachloropalladate(II), Na-2[PdCl4], in ethanol. The compounds were characterized by elemental analysis, FT-IR, H-1 NMR, UV-visible, and thermogravimetric analysis. The crystal structures of L-2 and 1-3 were determined by single-crystal X-ray diffraction. In 1-3, the geometry around palladium remains almost square planar, coordinated to carbon, nitrogen, and sulfur of the ligand forming a bichelated cyclopalladate complex. The C-H center dot center dot center dot Cl type intermolecular hydrogen bonds, weak pi center dot center dot center dot pi, C-H center dot center dot center dot pi, and van der Waals interactions are believed to be the stabilizing forces for the crystal packing of these palladacycles.
Keywords: 2-Thiobenzylazobenzene; CNS-donor ligand; crystal structure; Palladacycles; Thermogravimetric analysis

Synthesis, characterization and in vitro study of biocompatible cinnamaldehyde functionalized magnetite nanoparticles (CPGF Nps) for hyperthermia and drug delivery applications in breast cancer - Wani, Kirtee D.; Kadu, Brijesh S.; Mansara, Prakash; Gupta, Preeti; Deore, Avinash V.; Chikate, Rajeev C.; Poddar, Pankaj; Dhole, Sanjay D.; Kaul-Ghanekar, Ruchika (Plos One, 2014)
Cinnamaldehyde, the bioactive component of the spice cinnamon, and its derivatives have been shown to possess anticancer activity against various cancer cell lines. However, its hydrophobic nature invites attention for efficient drug delivery systems that would enhance the bioavailability of cinnamaldehyde without affecting its bioactivity. Here, we report the synthesis of stable aqueous suspension of cinnamaldehyde tagged Fe3O4 nanoparticles capped with glycine and pluronic polymer (CPGF NPs) for their potential application in drug delivery and hyperthermia in breast cancer. The monodispersed superparamagnetic NPs had an average particulate size of similar to 20 nm. TGA data revealed the drug payload of similar to 18%. Compared to the free cinnamaldehyde, CPGF NPs reduced the viability of breast cancer cell lines, MCF7 and MDAMB231, at lower doses of cinnamaldehyde suggesting its increased bioavailability and in turn its therapeutic efficacy in the cells. Interestingly, the NPs were non-toxic to the non-cancerous HEK293 and MCF10A cell lines compared to the free cinnamaldehyde. The novelty of CPGF nanoparticulate system was that it could induce cytotoxicity in both ER/PRpositive/Her2 negative (MCF7) and ER/PRnegative/Her2 negative (MDAMB231) breast cancer cells, the latter being insensitive to most of the chemotherapeutic drugs. The NPs decreased the growth of the breast cancer cells in a dose-dependent manner and altered their migration through reduction in MMP-2 expression. CPGF NPs also decreased the expression of VEGF, an important oncomarker of tumor angiogenesis. They induced apoptosis in breast cancer cells through loss of mitochondrial membrane potential and activation of caspase-3. Interestingly, upon exposure to the radiofrequency waves, the NPs heated up to 41.6 degrees C within 1 min, suggesting their promise as a magnetic hyperthermia agent. All these findings indicate that CPGF NPs prove to be potential nano-chemotherapeutic agents in breast cancer.

Synthesis, characterization and molecular structures of homologated analogs of 2-bromo-3-(n-alkylamino)-1,4-napthoquinone - Salunke-Gawali, Sunita; Pawar, Omkar; Nikalje, Milind; Patil, Rishikesh; Weyhermueller, Thomas; Puranik, Vedavati G.; Konkimalla, V. Badireenath (Journal of Molecular Structure, 2014)
Four analogues of 2-bromo-3-(n-alkylamino)-1,4-napthoquinone (where n-alkyl is methyl in L-1Br, ethyl in L-2Br, propyl in L-3Br and butyl in L-4Br) are synthesized and characterized. A reaction mechanism is proposed for the formation of L-1 Br to L-4Br from the starting material 2,3-dibromo-1,4-naphthoquinone. The v(N-H) frequency in the FT-IR spectra is affected by the intramolecular hydrogen bonding in L-1Br to L-4Br and is observed similar to 3267 cm(-1) in L-2Br. A shift of similar to 25 cm(-1) is observed in the v(C-Br) frequency in all the compounds as compared to 2,3-dibromo-1,4-naphthoquinone (627 cm(-1)). A broad charge transfer band is observed between 400 and 600 nm in the UV-Vis spectra, which imparts red colour to all the compounds. Molecular structures of L-2Br and L-3Br were studied by single crystal X-ray diffraction studies. Molecules of L-2Br crystallize in Pca2(1), whereas the molecule L-3Br crystallizes in the P-1 space group. Molecules of L-2Br forms a polymeric chain through N-H...O interaction and forms beautiful butterfly like arrangement of molecules when viewed down the `a' axis. Ladder like polymeric chain of molecules is observed in L-3Br via C-H...O and N-H...O interactions. Every alternating neighbouring chains of L-3Br, show pi-pi stacking interactions between the quinonoid rings of the molecules, however this interaction is not observed in L-2Br. (C) 2013 Elsevier B.V. All rights reserved.
Keywords: 2; 3-Dibromo-1; 4-naphthoquinone; Aminonaphthoquinone; hydrogen bonding; Michael addition; pi-pi stacking

Synthesis, characterization and photocatalytic behavior of TiO2-SiO2 mesoporous composites in hydrogen generation from water splitting - Niphadkar, P. S.; Chitale, S. K.; Sonar, S. K.; Deshpande, Suvarna S.; Joshi, P. N.; Awate, S. V. (Journal of Materials Science, 2014)
TiO2-SiO2 mesoporous composite photocatalysts with different proportions (in wt%) of TiO2 and SiO2 (TiO2-SiO2 = 20:80, 40:60, 60:40, 80:20 and 100:0) were prepared by loading TiO2 on as-synthesized Si-MCM-41 using sol-gel method. The physicochemical properties of composites were investigated by powder X-ray diffraction, N-2 adsorption-desorption measurements, transmission electron microscopy and UV-Vis diffuse reflectance spectroscopy. It is revealed that the titanium species are dispersed as TiO2 having interaction with the surface of the support. Even at high TiO2 loading, the mesostructural feature of MCM-41 was found to be intact without pore blockages. The change in morphology of TiO2 particle was observed with increase in TiO2 loading which may be due to different environment for the growth of TiO2. The photocatalytic evaluation of composites was carried out in production of hydrogen by water splitting. Among the prepared samples, mesoporous composite containing 60 % TiO2 (MTi60) has shown the best results (0.08805 mmol of H-2/h/g of TiO2) compared to other composite photocatalysts. The catalytic performance of this sample was further enhanced (similar to 8 times) after loading 1 % Pt in water splitting (0.70161 mmol of H-2/h/g of TiO2). 1 % Pt loaded on pure TiO2 (MTi100) showed hydrogen evolution of the magnitude 0.26 mmol of H-2/h/g of TiO2. TiO2-SiO2 mesoporous composite photocatalyst showed much higher activity (similar to 1.9 times) than amorphous silica-embedded titania catalyst having same composition.

Synthesis of 2,5-furandicarboxylic acid by the aerobic oxidation of 5-hydroxymethyl furfural over supported metal catalysts - Sahu, Ramakanta; Dhepe, Paresh Laxmikant (Reaction Kinetics Mechanisms and Catalysis, 2014)
Supported Pt catalysts are synthesized, characterized and are used in the liquid phase air oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). Under the optimum reaction conditions of a stepwise increase in the reaction temperature (75 and 140 degrees C for 12 h each), we achieved as high as 96 % FDCA yield in presence of 1 bar oxygen pressure over Pt/c-Al2O3. It is shown that as the oxygen pressure increases (1-10 bar), the FDCA yields decrease, since at higher partial pressure of oxygen, overoxidation reactions of substrate and product(s) are possible. It is interesting to note that even with air as an oxidant, we obtained similar yields of FDCA as that with oxygen. Moreover, the effects of base (weak or strong), its concentration (equimolar or excess) were studied in detail. It is important to increase the reaction temperature in a stepwise manner to achieve higher yields of FDCA since at higher temperatures HMF undergoes self-degradation and thus the yields of FDCA decrease. The self-degradation of HMF is also proved by undertaking the reaction under nitrogen environment. The study on the effect of substrate-to-catalyst ratio is done to improve up on the economics of overall process. The effect of supports (reducible and non-reducible) and their oxygen storage capacity is discussed and is proposed to be one of the factors to change the course of reaction. Furthermore, we have shown that FDCA formed in the reaction can be successfully isolated (91 %, isolated yield) in the pure form and its purity is confirmed by NMR, melting point, and elemental analysis. The catalysts were characterized with X-ray powder diffraction, transmission electron microscopy and inductively coupled plasma-optical emission spectroscopy techniques.
Keywords: Biomass; FDCA; green chemistry; heterogeneous catalyst; HMF; Impregnation; Oxidation

Synthesis of a recyclable and efficient Pd(II) 4-(2-pyridyl)-1,2,3-triazole complex over a solid periodic mesoporous organosilica support by ``click reactions'' for the stille coupling reaction - Sharma, Priti; Singh, A. P. (RSC Advances, 2014)
A highly efficient, reusable B-PMO-TZ-Pd(II) catalyst was synthesized by anchoring 4-(2-pyridyl)-4-(2-pyridyl)-1,2,3-triazole ligand over the surface of an organo-functionalized benzene support containing periodic mesoporous organosilica (B-PMO) via ``click reaction'' and the subsequent complexation with PdCl2. B-PMO materials with uniform hexagonal arrangements were prepared using C-16 alkyl trimethyl ammonium bromide [CTAB] surfactant under basic conditions. The physiochemical properties of the functionalised catalyst were analysed by elemental analysis, ICP-OES, XRD, N-2 sorption, TGA & DTA, solid state C-13, Si-29 NMR spectra, FT-IR, XPS, UV-vis, SEM and TEM. XRD and N-2 sorption revealed the morphological and textural properties of the synthesized catalyst, confirming that ordered mesoporous channel structure was retained even after the multistep synthetic procedure. The (100), (110) and (200) reflections in B-PMO are evidence of its good structural stability and the existence of long range order. The TGA-DTA results reveal that the synthesized catalyst B-PMO-TZ-Pd(II) was thermally stable, even at high temperature. The organic moieties anchored over the surface of B-PMO were demonstrated by solid state C-13 NMR and FT-IR spectroscopy. Solid state Si-29 NMR spectroscopy provides information about the degree of functionalization of the surface silanol group. The electronic environment and oxidation state of Pd in B-PMO-TZ-Pd(II) were monitored by XPS and UV-visible techniques. Moreover, the morphologies and topographic information of the synthesized B-PMO-TZ-Pd(II) catalyst were confirmed by SEM and TEM analyses. The catalytic properties of the catalyst for the Stille coupling reaction were screened, and higher catalytic activities with high TONs were observed. The anchored solid B-PMO-TZ-Pd(II) catalyst can be recycled efficiently and reused several (four) times without a major loss in reactivity.

Synthesis of alpha,beta-unsaturated delta-lactones by vinyl acetate mediated asymmetric cross-aldol reaction of acetaldehyde: mechanistic insights - Kumar, Manjeet; Kumar, Arvind; Rizvi, Masood; Mane, Manoj; Vanka, Kumar; Taneja, Subhash C.; Shah, Bhahwal Ali (European Journal of Organic Chemistry, 2014)
A tandem asymmetric cross-aldol reaction involving the in situ generation of acetaldehyde from vinyl acetate has been developed that may resolve the challenges associated with the handling of acetaldehyde. The simple protocol, mild reaction conditions and unique harmony of an organocatalyst with a biocatalyst make this method a valuable tool for the synthesis of asymmetric beta-hydroxy aldehydes. By using this methodology we have accessed alpha,beta-unstaurated delta-lactones as well as isochromenones with high enantioselectivities from both asymmetric beta-hydroxy aldehydes and ketones. Systemic density functional theory (DFT) studies were also performed to gain mechanistic insights into the role of hydrogen bonding in the asymmetric cross-aldol reaction of acetaldehyde and in the key cis/trans isomerisation step in the synthesis of d-lactones.
Keywords: Aldol reactions; asymmetric catalysis; lactones; reaction mechanisms

Synthesis of an efficient heteroatom-doped carbon electro-catalyst for oxygen reduction reaction by pyrolysis of protein-rich pulse flour cooked with SiO2 nanoparticles - Gokhale, Rohan; Unni, SreeKuttan M.; Puthusseri, Dhanya; Kurungot, Sreekumar; Ogale, Satishchandra (Physical Chemistry Chemical Physics, 2014)
Development of a highly durable, fuel-tolerant, metal-free electro-catalyst for oxygen reduction reaction (ORR) is essential for robust and cost-effective Anion Exchange Membrane Fuel Cells (AEMFCs). Herein, we report the development of a nitrogen-doped (N-doped) hierarchically porous carbon-based efficient ORR electrocatalyst from protein-rich pulses. The process involves 3D silica nanoparticle templating of the pulse flour(s) followed by their double pyrolysis. The detailed experiments are performed on gram flour (derived from chickpeas) without any in situ/ex situ addition of dopants. The N-doped porous carbon thus generated shows remarkable electrocatalytic activity towards ORR in the alkaline medium. The oxygen reduction on this material follows the desired 4-electron transfer mechanism involving the direct reduction pathway. Additionally, the synthesized carbon catalyst also exhibits good electrochemical stability and fuel tolerance. The results are also obtained and compared with the case of soybean flour having higher nitrogen content to highlight the significance of different parameters in the ORR catalyst performance.

Synthesis of chenopanone - Deore, Prashant S.; N. P. Argade (Indian Journal of Chemistry Section B-Organic Chemistry Including Medicinal Chemistry, 2014)
Starting from glyoxalic acid, a facile three step approach to chenopanone has been described utilizing the Barbier reaction as a key step.
Keywords: acid hydrolysis; Barbier reaction; chenopanone; condensation; Glyoxalic acid; isovaleraldehyde; synthesis

Synthesis of ciprofloxacin-conjugated poly(L-lactic acid) polymer for nanofiber fabrication and antibacterial evaluation - Parwe, Sharad P.; Chaudhari, Priti N.; Mohite, Kavita K.; Selukar, Balaji S.; Nande, Smita S.; Garnaik, Baijayantimala (International Journal of Nanomedicine, 2014)
Ciprofloxacin was conjugated with polylactide (PLA) via the secondary amine group of the piperazine ring using PLA and 7-(4-(2-Chloroacetyl) piperazin-1-yl)-1-cyclopropyl-6-fluoro-1, 4-dihydro-4-oxoquinoline-3-carboxylic acid. Zinc prolinate, a biocompatible catalyst was synthesized, characterized, and used in ring opening polymerization of L-lactide. Five different kinds of OH-terminated poly(L-lactide) (two-, three-, four-, six-arm, star-shaped) homopolymers were synthesized by ring opening polymerization of L-lactide in the presence of dodecanol, glycerol, pentaerythritol, dipentaerythritol as initiator and zinc prolinate as a catalyst. The structures of the polymers and conjugates were thoroughly characterized by means of gel permeation chromatography, matrix-assisted laser desorption/ionization-time of flight mass spectrometry, and nuclear magnetic resonance spectroscopy. PLA (molecular weight = 100,000) and ciprofloxacin conjugated PLA were used for fabrication of nonwoven nanofiber mat (diameter ranges; 150-400 nm) having pore size (62-102 nm) using electrospinning. The microbiological assessment shows that the release of ciprofloxacin possesses antimicrobial activity. The drug-release behavior of the mat was studied to reveal potential application as a drug delivery system. The result shows that the ciprofloxacin release rates of the PLA conjugate nonwoven nanofiber mat could be controlled by the drug loading content and the release medium. The development of a biodegradable ciprofloxacin system, based on nonwoven nanofiber mat, should be of great interest in drug delivery systems.
Keywords: antibacterial activity; ciprofloxacin conjugated polylactides; CP-PLA; drug release; electrospinning; MDR; nonwoven nanofibers; zinc prolinate

Synthesis of fatty monoester lubricant base oil catalyzed by Fe-Zn double-metal cyanide complex - Raut, Ravindra K.; Shaikh, Mehejabeen; Darbha, Srinivas (Journal of Chemical Sciences, 2014)
Fatty monoester lubricant base oils as high as 96.7 mol% were prepared by reacting methyl oleate with long-chain alcohols viz., 2-ethyl-1-hexanol (C-8-OH), 1-decanol (C10OH) and 1-dodecanol (C12OH) in the presence of a solid Fe-Zn double-metal cyanide (DMC) complex catalyst. Unlike many other acid catalysts, DMC doesn't produce undesired ether side products. The catalyst was reusable in four recycling experiments with little loss in catalytic activity and ester yield. The long-chain esters prepared in the study have the desired physical properties for their application as lubricant base oils.
Keywords: Fatty monoester; Fe-Zn double-metal cyanide (DMC) catalyst; lubricant base oil; transesterification

Synthesis of functionalized coumarins and quinolinones by NHC-catalyzed annulation of modified enals with heterocyclic C-H acids - Yetra, Santhivardhana Reddy; Roy, Tony; Bhunia, Anup; Porwal, Digvijay; Biju, Akkattu T. (Journal of Organic Chemistry, 2014)
N-Heterocyclic carbene (NHC) catalyzed lactonization and lactamization of 2-bromoenals with heterocyclic C–H acids proceeding via the α,β-unsaturated acyl azolium intermediates is reported. The reaction furnished coumarin- or quinolinone-fused lactone/lactam derivatives. In addition, results of the enantioselective version of this reaction using chiral NHC are presented.

Synthesis of green nano iron particles (GnIP) and their application in adsorptive removal of As(III) and As(V) from aqueous solution - Prasad, Kumar Suranjit; Gandhi, Pooja; Selvaraj, Kaliaperumal (Applied Surface Science, 2014)
{The present study reports a new approach to synthesise nano iron particles using leaf extract of Mint (Mentha spicata L.) plant. The synthesised GnIPs were subjected to detailed adsorption studies for removal of arsenite and arsenate from aqueous solution of defined concentration. Iron nanoparticles synthesised using leaf extract showed UV-vis absorption peaks at 360 and 430 nm. TEM result showed the formation of polydispersed nanoparticles of size ranging from 20 to 45 nm. Nanoparticles were found to have core-shell structure. The planer reflection of selected area electron diffraction (SAED) and XRD analysis suggested that iron particles were crystalline and belonged to fcc (face centred cubic) type. Energy-dispersive X-ray analysis (EDAX) shows that Fe was an integral component of synthesised nanoparticles. The content of Fe in nanoparticles was found to be 40%, in addition to other elements like C (16%), 0 (19%) and Cl (23%). FT-IR study suggested that functional groups like NH
Keywords: Adsorption; Arsenate; Arsenite; Iron nanoparticles; kinetics; M. spicata L.

Synthesis of (+)-harmicine - Mondal, Pravat; N. P. Argade (Synthesis-Stuttgart, 2014)
A facile convergent access to the important indole alkaloid (+)-harmicine is described, starting from tryptamine and (R)-acetoxysuccinic anhydride via the corresponding acetoxysuccinimide in very good overall yield. Regioselective reduction of an unsymmetrical imide carbonyl group and acid-catalyzed stereoselective intramolecular cyclization were the key features involved. The directing group to induce asymmetry was finally detached via the corresponding iodide by using tributyltin hydride chemistry.
Keywords: alkaloids; cyclization; imides; reduction; stereoselective synthesis

Synthesis of the central tricyclic core of the isatisine A: harmonious orchestration of [metal]-catalyzed reactions in a sequence - Patel, Pitambar; Reddy, B. Narendraprasad; Ramana, C. V. (Tetrahedron, 2014)
Two sequential metal-catalyzed transformations, involving [In]-catalyzed Friedel Crafts type addition of spiroaminol carbon to indole C3 followed by [Rh]-catalyzed dehydrogenative cyclization of the resulting gamma-amino alcohol culminated in the construction of the central tricyclic core isatisine A. The overall strategy employed three easily available starting compounds and delivered the complex tricyclic core in four steps with all four steps being catalytic in nature. (C) 2013 Elsevier Ltd. All rights reserved.
Keywords: Dehydrogenative cyclization; Friedel-Crafts reaction; Indium chloride; Isatisine A; Rhodium; Spiro-3-indolinone

Synthesis, spectroscopic characterization and structural investigations of new adduct compound of carbazole with picric acid: DNA binding and antimicrobial studies - Saravanabhavan, Munusamy; Sathya, Krishnan; Puranik, Vedavati G.; Sekar, Marimuthu (Spectrochimica Acta Part A-Molecular and Biomolecular Spectroscopy, 2014)
Carbazole picrate (CP), a new organic compound has been synthesized, characterized by various analytical and spectroscopic technique such as FT-IR, UV-Vis, H-1 and C-13 NMR spectroscopy. An orthorhombic geometry was proposed based on single crystal XRD study. The thermal stability of the crystal was studied by using thermo-gravimetric and differential thermal analyses and found that it was stable up to 170 degrees C. Further, the newly synthesized title compound was tested for its in vitro antibacterial and antifungal activity against various bacterial and fungal species. Also, the compound was tested for its binding activity with Calf thymus (CT) DNA and the results show a considerable interaction between CP and CT-DNA. (C) 2013 Elsevier B.V. All rights reserved.
Keywords: Antimicrobial activity and DNA-interaction; CP adduct; Single crystal XRD; TG-DTA

Synthesis, structure, spectral, electrochemical and sensing properties of 3-amino boron-dipyrromethene and its derivatives - Ganapathi, Emandi; Madhu, Sheri; Chatterjee, Tamal; Gonnade, Rajesh G.; Ravikanth, Mangalampalli (Dyes and Pigments, 2014)
We report the synthesis of 3-amino boron-dipyrromethene (3-amino BODIPY) by treating 3-bromo boron-dipyrromethene (3-bromo BODIPY) initially with sodium azide in acetonitrile followed by tri-phenylphosphine(PPh3)/H2O in tetrahydrofuran in three steps under mild reaction conditions. In this reaction, 3-azido BODIPY which formed in the first step was not isolated but the 3-iminophosphorane BODIPY which formed in the second step was isolated and characterized crystallographically. The 3-amino BODIPY was characterized by various spectroscopic and X-ray analytical techniques. To test the reactivity of amine functionality on BODIPY core, we prepared 1-(meso-anisyl BODIPY)-3-phenyl urea/thiourea derivatives under simple reaction conditions. Our studies indicated that 1-(meso-anisyl BODIPY)-3-pheny thiourea can act as specific chemodosimetric sensor for Hg2+ ion and 1-(meso-anisyl BODIPY)-3-phenyl urea as colorimetric and ratiometric sensor for F- ion. (C) 2013 Elsevier Ltd. All rights reserved.
Keywords: 3-Amino boron dipyrromethene; Chemodosimeter; F sensor; Fluorescent probes; Iminophosphorane BODIPY; Mercury(II) sensor

Synthetic precursor to vertical TiO2 nanowires - Mishra, Biswajit; Ghildiyal, P.; Agarkar, Shruti A.; Khushalani, Deepa (Materials Research Express, 2014)
An easy protocol for improvement in formation of the photoanode in a dye sensitized solar cell is addressed. Specifically, a novel synthesis for the formation of a TiO2 precursor: titanium butanediolate, is detailed. This precursor is found to have higher thermal and temporal stability than commercially available TiO2 precursors and it has successfully been employed in the one-pot synthesis of rutile nanowires grown directly on a conducting substrate: fluorine doped tin oxide (FTO). This synthesis has been further extended to directly form a mixed phase TiO2 film consisting of rutile nanowires along with anatase spherical particles on FTO and this assembly has been used as the photoanode in a dye-sensitized solar cell. The synergistic effect of the two phases has provided a net DSSC efficiency of 4.61% with FF = 61%.
Keywords: Nanomaterials; Nanowires; TiO2

Synthetic turn mimetics and hairpin nucleators: quo vadimus? - Nair, Roshna V.; Baravkar, Sachin B.; Ingole, Tukaram S.; Sanjayan, Gangadhar J. (Chemical Communications, 2014)
Structural mimicry of peptides has witnessed perceptible progress in the last three decades. Reverse turn and beta-hairpin units are the smallest secondary structural motifs that are some of the most scrutinized functional cores of peptides and proteins. The practice of mimicking, without altering the function of the bioactive core, ranges from conformational locking of the basic skeleton to total replacement of structural architecture using synthetic analogues. Development of heterogeneous backbones - using unnatural residues in place of natural ones - has broadened further opportunities for efficient structural rigidification. This feature article endeavours to trail the path of progress achieved hitherto and envisage the possibilities that lie ahead in the development of synthetic turn mimetics and hairpin nucleators.

Systematic evaluation of tetra-n-butyl ammonium bromide (TBAB) for carbon dioxide capture employing the clathrate process - Babu, Ponnivalavan; Chin, Weng Inn; Kumar, Rajnish; Linga, Praveen (Industrial & Engineering Chemistry Research, 2014)
Hydrate based gas separation (HBGS) process for the precombustion capture of CO2 from a fuel gas mixture is a novel method being investigated among the carbon capture and sequestration techniques to reduce CO2 emissions. The efficiency of the HGBS process can be improved by using promoters that reduce the formation pressure of mixed gas hydrates. In this study the effect of tetra-n-butyl ammonium bromide (TBAB) was systematically investigated at a constant temperature of 279.2 K and pressure of 6.0 MPa for different TBAB concentrations of 0.3, 1.0, 1.5, 2.0, and 3.0 mol %, respectively. The 0.3 mol % solutions had a relatively longer average induction time of 20.1 min but exhibited the highest total normalized gas uptake of 0.0104 (+/- 0.0004) mol of gas/mol of water and highest separation factor of 41.51 (+/- 6.391). On the other hand, the 1.0 mol % solution had very short average induction time (<0.5 min) and it had the highest hydrate growth rate of 60.8 (+/- 9.89) mol of gas. min(-1).m(-3), with the separation factor of 13.78 (+/- 3.30). Gas solubility measurements and microscopic images of the hydrate formation were also presented to provide greater insights into the effect of TBAB concentration on the gas uptake.

SBA-15-oxynitrides as a solid-base catalyst: effect of nitridation temperature on catalytic activity - Singh, Baljeet; Mote, Kaustubh R.; Gopinath, Chinnakonda S.; Madhu, Perunthiruthy K.; Polshettiwar, Vivek (Angewandte Chemie-International Edition, 2015)
Solid bases, such as SBA-15-oxynitrides, have attracted considerable interest for potential applications as catalysts in important industrial processes. Reported herein is that by simply tuning the temperature of nitridation (ammonolysis), the catalytic activity of these solid bases can be enhanced. Solid-state NMR spectroscopy and XPS studies provided the reasoning behind this change in activity.
Keywords: heterogeneous catalysis; Nanostructures; NMR spectroscopy; photoelectron spectroscopy; solid-state structures

Seeded on-surface supramolecular growth for large area conductive donor-acceptor assembly - Goudappagouda; Chithiravel, Sundaresan; Krishnamoorthy, Kothandam; Gosavi, Suresh W.; Babu, Sukumaran Santhosh (Chemical Communications, 2015)
Charge transport features of organic semiconductor assemblies are of paramount importance. However, large-area extended supramolecular structures of donor-acceptor combinations with controlled self-assembly pathways are hardly accessible. In this context, as a representative example, seeded on-surface supramolecular growth of tetrathiafulvalene and tetracyano-p-quinodimethane (TTF-TCNQ) using active termini of solution-formed sheaves has been introduced to form an extended assembly. We demonstrate for the first time, the creation of a large-area donor-acceptor assembly on the surface, which is practically very tedious, using a seeded, evaporation-assisted growth process. The excellent molecular ordering in this assembly is substantiated by its good electrical conductivity (similar to 10(-2) S cm(-1)). The on-surface assembly via both internally formed and externally added sheaf-like seeds open new pathways in supramolecular chemistry and device applications.

Selective aerobic oxidation of alcohols over Au-Pd/sodium titanate nanotubes - Nepak, Devadutta; Darbha, Srinivas (Catalysis Communications, 2015)
catalytic application of Au-Pd nanoparticles supported on sodium titanate nanotubes (NaTNTs) for liquid-phase aerobic oxidation of alcohols is reported, for the first time. This reaction occurs at 80-120 degrees C, 1 atm and solvent-/alkali-free conditions yielding the corresponding carbonyls in high selectivity. This catalyst was reusable and found to be more active/selective than the corresponding monometallic Au and Pd catalysts and Au-Pd/TiO2. Higher dispersion, smaller particle size and higher amount of electron density at gold are the causes for the superior activity of Au-Pd/NaTNT catalyst. (C) 2014 Elsevier B.V. All rights reserved.
Keywords: aerobic oxidation; Alcohol; Bimetallic Au-Pd catalyst; Sodium titanate nanotubes; TiO2

Selective and sensitive sensing of free bilirubin in human serum using water-soluble polyfluorene as fluorescent probe - Senthilkumar, T.; Asha, S. K. (Macromolecules, 2015)
The adherence of serum protein on conjugated polymer is a major bottleneck in the application of the latter for selective sensing of small biomolecules in blood serum. In this report, we present new polyfluorenes with d-glucuronic acid appendage that is a nonreceptor for any serum protein, thereby providing a platform for selective sensing of free bilirubin in the clinically relevant range of <25 to >50 mu mol/L in human blood serum. The appended d-glucuronic acid formed noncovalent interactions with bilirubin, which in conjunction with favorable spectral overlap between the polymers and bilirubin facilitated efficient FRET process in aqueous solutions. Addition of bilirubin resulted in the quenching of the polyfluorene emission with simultaneous appearance of bilirubin emission exhibiting visual emission color change from blue to light green. The polymer remained stable in serum even under severe basic conditions and exhibited high selectivity with visual sensitivity only toward free bilirubin in human serum in the presence of crucial interferences such as hemoglobin, proteins, biliverdin, glucose, cholesterol, and metal ions. Nanomolar sensing of bilirubin could also be demonstrated successfully using one of the d-glucuronic acid appended polymer (PF-Ph-GlcA), which could sense similar to 150 nm of bilirubin in human serum. The combined role of energy transfer and noncovalent interaction highlights the potential of the new polymer design for highly selective sensing activity in complex biofluids.

Selective inhibition of miR-21 by phage display screened peptide - Bose, Debojit; Nahar, Smita; Rai, Manish Kumar; Ray, Arjun; Chakraborty, Kausik; Maiti, Souvik (Nucleic Acids Research, 2015)
miRNAs are nodal regulators of gene expression and deregulation of miRNAs is causally associated with different diseases, including cancer. Modulation of miRNA expression is thus of therapeutic importance. Small molecules are currently being explored for their potential to downregulate miRNAs. Peptides have shown to have better potency and selectivity toward their targets but their potential in targeting and modulating miRNAs remain unexplored. Herein, using phage display we found a very selective peptide against pre-miR-21. Interestingly, the peptide has the potential to downregulate miR-21, by binding to pre-miR-21 and hindering Dicer processing. It is selective towards miR-21 inside the cell. By antagonising miR-21 function, the peptide is able to increase the expression of its target proteins and thereby increase apoptosis and suppress cell proliferation, invasion and migration. This peptide can further be explored for its anti-cancer activity in vivo and may be even extended to clinical studies.

Selective interfacial synthesis of metal-organic frameworks on a polybenzimidazole hollow fiber membrane for gas separation - Biswal, Bishnu P.; Bhaskar, Anand; Banerjee, Rahul; Kharul, Ulhas K. (Nanoscale, 2015)
Metal-organic frameworks (MOFs) have gained immense attention as new age materials due to their tuneable properties and diverse applicability. However, efforts on developing promising materials for membrane based gas separation, and control over the crystal growth positions on polymeric hollow fiber membranes still remain key challenges. In this investigation, a new, convenient and scalable room temperature interfacial method for growing MOFs (ZIF-8 and CuBTC) on either the outer or inner side of a polybenzimidazole based hollow fiber (PBI-BuI-HF) membrane surface has been achieved in a controlled manner. This was made possible by the appropriate selection of an immiscible solvent pair and the synthetic conditions. The growth of MOFs on the PBI-BuI-HF membrane by the interfacial method was continuous and showed an appreciable gas separation performance, conveying promise for their applicability.

Self-assembled vertically aligned gold nanorod super-lattices for ultra-high sensitive detection of molecules - Apte, Amey; Bhaskar, Prashant; Das, Raja; Chaturvedi, Smita; Poddar, Pankaj; Kulkarni, Sulabha (Nano Research, 2015)
We show that self-assembled vertically aligned gold nanorod (VA-GNRs) superlattices can serve as probes or substrates for ultra-high sensitive detection of various molecules. D-glucose and 2,4,6-trinitrotoluene (TNT) have been chosen as model systems due to their very low Raman cross-sections (5.6 x 10(-30) cm(2).molecule(-1).sr(-1) for D-glucose and 4.9 x 10(-31) cm(2). molecule(-1).sr(-1) for TNT) to show that the VA-GNR superlattice assembly offers as low as yoctomole sensitivity. Our experiment on mixed samples of bovine serum albumin (BSA) and D-glucose solutions demonstrate sensitivity for the latter, and the possible extension to real samples. Self-assembled superlattices of VA-GNRs were achieved on a silicon wafer by depositing a drop of solvent containing the GNRs and subsequent solvent evaporation in ambient conditions. An additional advantage of the VA-GNR monolayers is their extremely high reproducible morphology accompanied by ultrahigh sensitivity which will be useful in many fields where a very small amount of analyte is available. Moreover the assembly can be reused a number of times after removing the already present molecules. The method of obtaining VA-GNRs is simple, inexpensive and reproducible. With the help of simulations of monolayers and multilayers it has been shown that superlattices can achieve better sensitivity than monolayer assembly of VA-GNRs.
Keywords: Nanostructures; Raman spectroscopy; self-assemblies; sensors; superlattices

Self-assembly directed template photopolymerization of perylenebisimide-poly (4-vinylpyridine): nano organization - Shinde, Shekhar; Asha, S. K. (Polymer, 2015)
A perylene bisimide derivative (PDP-UPBIAcry) having hydroxyl moieties at one termini and polymerizable acrylic units at the other termini was supramolecularly complexed with the pyridine units of Poly (4-vinyl pyridine) (P4VP), followed by photoinduced polymerization of the acrylic units to obtain lamellar organization in the <10 nm range. H-1 NMR studies including variable temperature (20 degrees C-70 degrees C) measurements were undertaken in DMSO-d(6) (anhydrous, extra dry) to understand the interaction between PDP-UPBIAcry and P4VP. The aromatic perylene protons of PDP-UPBIAcry registered an upfield chemical shift while the pyridine protons of P4VP exhibited small downfield shift in their 1:1 supramolecular complex. The hydrogen bonding interaction between pyridyl nitrogen and phenolic OH group was also traced in non-polar media like CDCl3 in model complexes of 4-vinyl pyridine (4VP) with PDP-UPBIAcry. Wide angle X-ray diffraction (WXRD) technique was used to study the bulk structure. Transmission electron microscopy (TEM) imaging revealed highly ordered layered assembly formed upon complexation. Observation from DFT energy minimization studies were correlated with X-ray diffraction data of the supramolecular complex [P4VP (PDP-UPBIAcry)](1.0) to understand the nature of packing of PDP-UPBIAcry that lead to the formation of highly ordered lamellar stacks alternating with P4VP. The higher ordering in the supramolecular polymer complex was also confirmed by the quenching of fluorescence and reduced fluorescence life times of thin solid films of the [P4VP Poly(PDP-UPBIAcry)](1.0) sample. (C) 2015 Elsevier Ltd. All rights reserved.
Keywords: hydrogen bonding; P4VP; Perylenebisimide

Self-assembly of phospholipids on flat supports - Mhashal, Anil R.; Roy, Sudip (Physical Chemistry Chemical Physics, 2015)
The current study deals with the self-assembly of phospholipids on flat supports using the Martini coarse grain model. We reported here the effect of the hydrophilic and hydrophobic nature of the solid supports on the lipid self-assembly. The hydrophilic and hydrophobic supports were modeled on the basis of water droplet simulations. The present work addresses the self-assembly mechanism of lipids on eight different supports with different strengths of hydrophilicity and hydrophobicity. We demonstrated how interplay between the interactions of lipid and water with the support can guide the lipid self-assembly process. Thereafter, we calculated the energetics of the components of the system to quantify the competitions between water and a lipid head-group with hydrophilic supports. Finally, the properties of the self-assembled bilayers were also analyzed and reported here.

Self-similar rupture of thin free films of power-law fluids - Thete, Sumeet Suresh; Anthony, Christopher; Basaran, Osman A.; Doshi, Pankaj (Physical Review E, 2015)
The rupture of a thin free film of a power-law fluid under the competing influences of destabilizing van der Waals pressure and stabilizing surface tension pressure is analyzed. In such a fluid, viscosity decreases with the deformation rate raised to the n - 1 power where 0 < n <= 1 (n = 1 for a Newtonian fluid). When 6/7 < n <= 1, film rupture occurs under a balance between van der Waals pressure, inertial stress, and viscous stress. When n < 6/7, however, the dominant balance changes: Viscous stress becomes negligible and the film ruptures under the competition between van der Waals pressure, inertial stress, and surface tension pressure.

Self-templated chemically stable hollow spherical covalent organic framework - Kandambeth, Sharath; Venkatesh, V.; Shinde, Digambar B.; Kumari, Sushma; Halder, Arjun; Verma, Sandeep; Banerjee, Rahul (Nature Communications, 2015)
Covalent organic frameworks are a family of crystalline porous materials with promising applications. Although active research on the design and synthesis of covalent organic frameworks has been ongoing for almost a decade, the mechanisms of formation of covalent organic frameworks crystallites remain poorly understood. Here we report the synthesis of a hollow spherical covalent organic framework with mesoporous walls in a single-step template-free method. A detailed time-dependent study of hollow sphere formation reveals that an inside-out Ostwald ripening process is responsible for the hollow sphere formation. The synthesized covalent organic framework hollow spheres are highly porous (surface area similar to 1,500m(2) g(-1)), crystalline and chemically stable, due to the presence of strong intramolecular hydrogen bonding. These mesoporous hollow sphere covalent organic frameworks are used for a trypsin immobilization study, which shows an uptake of 15.5 mu mol g(-1) of trypsin.

Sequence and structure-based comparative analysis to assess, identify and improve the thermostability of penicillin G acylases - Panigrahi, Priyabrata; Chand, Deepak; Mukherji, Ruchira; Ramasamy, Sureshkumar; Suresh, C. G. (Journal of Industrial Microbiology & Biotechnology, 2015)
Penicillin acylases are enzymes employed by the pharmaceutical industry for the manufacture of semi-synthetic penicillins. There is a continuous demand for thermostable and alkalophilic enzymes in such applications. We have carried out a computational analysis of known penicillin G acylases (PGAs) in terms of their thermostable nature using various protein-stabilizing factors. While the presence of disulfide bridges was considered initially to screen putative thermostable PGAs from the database, various other factors such as high arginine to lysine ratio, less content of thermolabile amino acids, presence of proline in beta-turns, more number of ion-pair and other non-bonded interactions were also considered for comparison. A modified consensus approach designed could further identify stabilizing residue positions by site-specific comparison between mesostable and thermostable PGAs. A most likely thermostable enzyme identified from the analysis was PGA from Paracoccus denitrificans (PdPGA). This was cloned, expressed and tested for its thermostable nature using biochemical and biophysical experiments. The consensus site-specific sequence-based approach predicted PdPGA to be more thermostable than Escherichia coli PGA, but not as thermostable as the PGA from Achromobacter xylosoxidans. Experimental data showed that PdPGA was comparatively less thermostable than Achromobacter xylosoxidans PGA, although thermostability factors favored a much higher stability. Despite being mesostable, PdPGA being active and stable at alkaline pH is an advantage. Finally, several residue positions could be identified in PdPGA, which upon mutation selectively could improve the thermostability of the enzyme.
Keywords: Alkalistable; beta-lactam antibiotics; Consensus approach; Disulfide bridge; Ion pairs; Penicillin acylase; Thermostability

Shape-selective oriented cerium oxide nanocrystals permit assessment of the effect of the exposed facets on catalytic activity and oxygen storage capacity - Sreeremya, Thadathil S.; Krishnan, Asha; Remani, Kottayilpadi C.; Patil, Kashinath R.; Brougham, Dermot F.; Ghosh, Swapankumar (ACS Applied Materials & Interfaces, 2015)
The catalytic performance of a range of nanocrystalline CeO2 samples, prepared to have different morphologies, was measured using two accepted indicators; oxygen storage and diesel soot combustion. The same powders were characterized hi detail by HR-TEM, XRD, XPS, and Raman methods. The study demonstrates that activity is determined by the relative fraction of the active crystallographic planes, not by the specific surface area of the powders. The physical study is a step toward quantitative evaluation of the relative contribution to activity of the different facets. The synthetic protocol permits fabrication of CeO2 nanostructures with preferentially grown active planes, and therefore has potential in developing catalytic applications and in nanocompositing.
Keywords: ceria; chemical activities; crystal facets; nanocrystals; texture coefficient

Short enantioselective synthesis of ephedrine, amphetamine and their analogues via two stereocentered Co(III)-catalyzed hydrolytic kinetic resolution of racemic syn-benzyloxy epoxide - Lalwani, Komal G.; Sudalai, Arumugam (Tetrahedron Letters, 2015)
An efficient route for the synthesis of 6 drugs belonging to phenethylamine and amphetamine classes in excellent overall yields and high optical purity has been described. The strategy involves introduction of stereogenic centers by means of two-stereocentered Co(III)-catalyzed hydrolytic kinetic resolution (HKR) of racemic syn-benzyloxy epoxide followed by Pd-catalyzed regioselective cationic hydrogenation of amino alcohols as the key reactions. (C) 2015 Elsevier Ltd. All rights reserved.
Keywords: Amphetamine; Cationic hydrogenation; Hydrolytic kinetic resolution; Phenethylamine; Stereogenic centers

Silica microspheres containing high density surface hydroxyl groups as efficient epoxidation catalysts - Chandra, Prakash; Doke, Dhananjay S.; Shubhangi B. Umbarkar; Vanka, Kumar; Biradar, Ankush V. (RSC Advances, 2015)
Uniformly sized silica microspheres were synthesized by a hydrolysis-condensation method. The obtained material was etched with a mild aqueous potassium hydroxide solution for different periods of time to break their Si-O-Si bonds and increases the density of hydroxyl groups on their surfaces. The resulting materials were then used as transition metal-free catalysts for oxidation of olefins in the presence of hydrogen peroxide as a green oxidant. The materials were thoroughly characterized using various physicochemical techniques. These highly populated hydroxyl groups on the surface of silica microspheres were proven to be responsible for excellent conversion (up to 93%) and epoxide selectivity (up to 100%) for various olefins. Quantum mechanical calculations also corroborate the experimental findings. Furthermore, both experimental and theoretical studies show that tertiary silanols were present at the active sites of the catalyst surface and were responsible for olefin epoxidation.

Silicon incorporated morpholine antifungals: design, synthesis, and biological evaluation - Jachak, Gorakhnath R.; Ramesh, Remya; Sant, Duhita G.; Jorwekar, Shweta U.; Jadhav, Manjusha R.; Tupe, Santosh G.; Deshpande, Mukund V.; Reddy, D. Srinivasa (ACS Medicinal Chemistry Letters, 2015)
Known morpholine class antifungals (fenpropimorph, fenpropidin, and amorolfine) were synthetically modified through silicon incorporation to have 15 sila-analogues. Twelve sila-analogues exhibited potent antifungal activity against different human fungal pathogens such as Candida albicans, Candida glabrata, Candida tropicalis, Cryptococcus neoformans, and Aspergillus niger. Si la-analogue 24 (fenpropimorph analogue) was the best in our hands, which showed superior fungicidal potential than fenpropidin, fenpropimorph, and amorolfine. The mode of action of sila-analogues was similar to morpholines, i.e., inhibition of sterol reductase and sterol isomerase enzymes of ergosterol synthesis pathway.
Keywords: Antifungal drugs; Candida albicans; ergosterol biosynthesis; morpholines; sila-analogues

Simple method for the preparation of ultra-small palladium nanoparticles and their utilization for the hydrogenation of terminal alkyne groups to alkanes - Seth, Jhumur; Kona, Chandrababu Naidu; Das, Shyamsundar; Bhagavatula L. V. Prasad (Nanoscale, 2015)
A simple and convenient method for the preparation of ultra-small palladium nanoparticles (Pd-NPs) by a modified digestive ripening method is described. These nanoparticles catalyse the hydrogenation of the terminal alkyne groups to alkanes selectively, and show no effect on other labile protecting and internal alkyne or internal/external alkene groups present in the molecule.

Simple recovery of intracellular gold nanoparticles from peanut seedling roots - Raju, D.; Mehta, Urmil J.; Ahmad, Absar (Journal of Nanoscience and Nanotechnology, 2015)
Fabrication of inorganic nanomaterials via a biological route witnesses the formation either extracellularly, intracellulary or both. Whereas extracellular formation of these nanomaterials is cherished owing to their easy and economical extraction and purification processes; the intracellular formation of nanomaterials, due to the lack of a proper recovery protocol has always been dreaded, as the extraction processes used so far were tedious, costly, time consuming and often resulting in very low recovery. The aim of the present study was to overcome the problems related with the extraction and recovery of intracellularly synthesized inorganic nanoparticles, and to devise a method to increasing the output, the shape, size, composition and dispersal of nanoparticles is not altered. Water proved to be much better system as it provided well dispersed, stable gold nanoparticles and higher recovery. This is the first report, where intracellular nanoparticles have been recovered using a very cost-effective and eco-friendly approach.
Keywords: gold nanoparticles; Peanut; Recovery; Sonication; Water

Single crystal-to-single crystal site-selective postsynthetic metal exchange in a Zn-MOF based on semi-rigid tricarboxylic acid and access to bimetallic MOFs - Bajpai, Alankriti; Chandrasekhar, Pujari; Govardhan, Savitha; Banerjee, Rahul; Moorthy, Jarugu Narasimha (Chemistry-A European Journal, 2015)
The metal ions in a neutral Zn-MOF constructed from tritopic triacid H3L with inherent concave features, rigid core, and peripheral flexibility are found to exist in two distinct SBUs, that is, 0D and 1D. This has allowed site-selective postsynthetic metal exchange (PSME) to be investigated and reactivities of the metal ions in two different environments in coordination polymers to be contrasted for the first time. Site-selective transmetalation of Zn ions in the discrete environment is shown to occur in a single crystal-to-single crystal (SCSC) fashion, with metal ions such as Fe3+, Ru3+, Cu2+, Co2+, etc., whereas those that are part of 1D SBU sustain structural integrity, leading to novel bimetallic MOFs, which are inaccessible by conventional approaches. To the best of our knowledge, site-selective postsynthetic exchange of an intraframework metal ion in a MOF that contains metal ions in discrete as well as polymeric SBUs is heretofore unprecedented.
Keywords: coordination polymers; metal-exchange; metal-organic frameworks; Metathesis; X-ray crystallography

Single-layer graphene doping through molecular interaction: field-effect transistor and atomic force microscopy investigations - Late, Dattatray J. (Advanced Device Materials, 2015)
The single-layer graphene has attracted considerable attention for the promising applications in new generation nanoelectronics and optoelectronics devices because of the high deal carrier mobility. Present investigations deal with the effect of chemical/molecular doping with varying the concentration of strong electron acceptor molecule such as tetracyanoethylene (TCNE) on transfer characteristics of single-layer graphene transistor. The Dirac point shift toward the positive gate voltage as a function of increasing concentration of TCNE molecules clearly indicates that the graphene is P-type doped. Our results indicate that the fermi energy level can be controlled by the amount of molecular doping in order to obtain graphene transistors with tunable Dirac points, which can be easily configured into functional nanoelectronic devices.

Single-layer graphene-assembled 3D porous carbon composites with PVA and Fe3O4 nano-fillers: an interface-mediated superior dielectric and EMI shielding performance - Rao, B. V. Bhaskara; Yadav, Prasad; Aepuru, Radhamanohar; Panda, H. S.; Ogale, Satishchandra; Kale, S. N. (Physical Chemistry Chemical Physics, 2015)
In this study, a novel composite of Fe3O4 nanofiller-decorated single-layer graphene-assembled porous carbon (SLGAPC) with polyvinyl alcohol (PVA) having flexibility and a density of 0.75 g cm(-3) is explored for its dielectric and electromagnetic interference (EMI) response properties. The composite is prepared by the solution casting method and its constituents are optimized as 15 wt% SLGAPC and 20 wt% Fe3O4 through a novel solvent relaxation nuclear magnetic resonance experiment. The PVA-SLGAPC-Fe3O4 composite shows high dielectric permittivity in the range of 1 Hz-10 MHz, enhanced by a factor of 4 as compared to that of the PVA-SLGAPC composite, with a reduced loss by a factor of 2. The temperature dependent dielectric properties reveal the activation energy behaviour with reference to the glass transition temperature (80 degrees C) of PVA. The dielectric hysteresis with the temperature cycle reveals a remnant polarization. The enhanced dielectric properties are suggested to be the result of improvement in the localized polarization of the integrated interface system (Maxwell-Wagner-Sillars (MWS) polarization) formed by the uniform adsorption of Fe3O4 on the surface of SLGAPC conjugated with PVA. The EMI shielding property of the composite with a low thickness of 0.3 mm in the X-band (8.2-12.4 GHz) shows a very impressive shielding efficiency of similar to 15 dB and a specific shielding effectiveness of 20 dB (g cm(-3))(-1), indicating the promising character of this material for flexible EMI shielding applications.

Singlet-triplet gaps in polyacenes: a delicate balance between dynamic and static correlations investigated by spin-flip methods - Ibeji, Collins U.; Ghosh, Debashree (Physical Chemistry Chemical Physics, 2015)
Over the last few years people have been interested in the process of singlet fission, owing to its relevance to solar cell technology. The energetics of singlet fission is intimately related to singlet-triplet (ST) gaps and energies of singlet excited states. However, accurate calculations of ST gaps in polyacenes are complicated due to near degeneracies in the pi orbitals, and therefore, have been quite challenging. The spin-flip equation-of-motion coupled-cluster (SF-EOM-CC) and its perturbative approximation have been shown to correctly treat situations involving electronic degeneracies and near degeneracies. In this work, we use various spin-flip methods to benchmark the ST gaps of small polyacenes and show that the error in the ST gaps with respect to the experiment is small and does not increase appreciably with the system size. The diradical and polyradical character of the polyacene ground states increase with the system size. However, for the small polyacenes the open-shell character of the ground state is still small enough to be treated using single reference methods.

Situ preparation of N-TiO2/graphene nanocomposite and its enhanced photocatalytic hydrogen production by H2S splitting under solar light - Bhirud, Ashwini P.; Sathaye, Shivaram D.; Waichal, Rupali P.; Ambekar, Jalindar D.; Park, Chan-J.; Kale, Bharat B. (Nanoscale, 2015)
Highly monodispersed nitrogen doped TiO2 nanoparticles were successfully deposited on graphene (N-TiO2/Gr) by a facile in-situ wet chemical method for the first time. N-TiO2/Gr has been further used for photocatalytic hydrogen production using a naturally occurring abundant source of energy i.e. solar light. The N-TiO2/Gr nanocomposite composition was optimized by varying the concentrations of dopant nitrogen and graphene (using various concentrations of graphene) for utmost hydrogen production. The structural, optical and morphological aspects of nanocomposites were studied using XRD, UV-DRS, Raman, XPS, FESEM, and TEM. The structural study of the nanocomposite shows existence of anatase N-TiO2. Further, the details of the components present in the composition were confirmed with Raman and XPS. The morphological study shows that very tiny, 7-10 nm sized, N-TiO2 nanoparticles are deposited on the graphene sheet. The optical study reveals a drastic change in absorption edge and consequent total absorption due to nitrogen doping and presence of graphene. Considering the extended absorption edge to the visible region, these nanocomposites were further used as a photocatalyst to transform hazardous H2S waste into eco-friendly hydrogen using solar light. The N-TiO2/Gr nanocomposite with 2% graphene exhibits enhanced photocatalytic stable hydrogen production i.e. similar to 5941 mu mol h(-1) under solar light irradiation using just 0.2 gm nanocomposite, which is much higher as compared to P25, undoped TiO2 and TiO2/Gr nanocomposite. The enhancement in the photocatalytic activity is attributed to `N' doping as well as high specific surface area and charge carrier ability of graphene. The recycling of the photocatalyst shows a good stability of the nanocomposites. This work may provide new insights to design other semiconductor deposited graphene novel nanocomposites as a visible light active photocatalyst.

Situ preparation of N-ZnO/graphene nanocomposites: excellent candidate as a photocatalyst for enhanced solar hydrogen generation and high performance supercapacitor electrode - Bhirud, Ashwini P.; Sathaye, Shivaram; Waichal, Rupali; Park, Chan-Jin; Kale, Bharat (Journal of Materials Chemistry A, 2015)
We have demonstrated a facile in situ wet chemical method to synthesize nanostructured nitrogen doped ZnO/Graphene (N-ZnO/GR) nanocomposites for the first time. Nitrogen doped ZnO over graphene (N-ZnO/GR) was studied using various concentrations of graphene. During the synthesis of N-ZnO/GR nanocomposites, in situ formation of graphene via GO reduction and formation of 4-9 nm N-ZnO have been demonstrated. The composite N-ZnO/GR absorbs in the visible region and this property is used for the photocatalytic reaction to transform hazardous H2S waste into eco-friendly hydrogen using solar light. The N-ZnO/GR nanocomposite with 0.3% graphene exhibits an enhanced photocatalytic stable hydrogen production rate i.e. similar to 5072 mu mol h(-1) under visible light irradiation. It is noteworthy that the N-ZnO/GR electrode exhibits a high specific capacitance of 555 F g(-1) and excellent cyclic performance with nearly 96.20% capacity retention after 2000 cycles at a current density of 10 A g(-1). These results indicate great potential applications of N-ZnO/GR in developing high hydrogen production and supercapacitors with high energy and power densities.

Sodium periodate mediated oxidative transformations in organic synthesis - Sudalai, Arumugam; Khenkin, Alexander; Neumann, Ronny (Organic & Biomolecular Chemistry, 2015)
The investigation of new oxidative transformations for the synthesis of carbon-heteroatom and heteroatom-heteroatom bonds is of fundamental importance in the synthesis of numerous bioactive molecules and fine chemicals. In this context, NaIO4, an exciting reagent, has attracted increasing attention enabling the development of these unprecedented oxidative transformations that are difficult to achieve otherwise. Thus, NaIO4 has been successfully explored as a versatile oxidant for a variety of fundamental organic transformations such as C-H activation, oxidative functionalization of alkenes and other interesting oxidative transformations and its application in the synthesis of bioactive natural products. This review summarizes recent developments in this area with NaIO4 as a versatile oxidant and brings out many challenges that still remain elusive for the future.

Solid state organic amine detection in a photochromic porous metal organic framework - Mallick, Arijit; Garai, Bikash; Addicoat, Matthew A.; Petkov, Petko St.; Heine, Thomas; Banerjee, Rahul (Chemical Science, 2015)
A new Mg(II) based photochromic porous metal-organic framework (MOF) has been synthesized bearing naphthalenediimide (NDI) chromophoric unit. This MOF (Mg-NDI) shows instant and reversible solvatochromic behavior in presence of solvents with different polarity. Mg-NDI also exhibits fast and reversible photochromism via radical formation. Due to the presence of electron deficient NDI moiety, this MOF exhibits selective organic amine (electron rich) sensing in solid state. The organic amine detection has been confirmed by photoluminescence quenching experiment and visual color change.

Solvent free one-pot multi-component synthesis of beta-azaarene substituted ketones via a Sn-catalyzed C(sp(3))-H functionalization of 2-alkylazaarenes - Chavan, Santosh S.; Pathan, Mohsinkhan Y.; Mulla, Shafeek A. R. (RSC Advances, 2015)
A tin-catalyzed solvent free one-pot multi-component cascade reaction strategy for the direct Michael addition/C(sp(3))-H functionalization of 2-alkylazaarenes with aldehydes and ketones via an aldol reaction has been developed. This is the first report and provides cost effective new access to potent biologically/medicinally important azaarene derivatives with high atom economy.

Solvent-free carbonylation of glycerol with urea using metal loaded MCM-41 catalysts - Kondawar, S. E.; Potdar, A. S.; Rode, C. V. (RSC Advances, 2015)
Reacting glycerol with urea is the most attractive option for the production of glycerol carbonate (GC) as it utilizes two inexpensive chemicals readily available in the chemical cycle. The overall result is the chemical fixation of carbon dioxide. A Zn/MCM-41(im) catalyst prepared by a wet impregnation method exhibited excellent activity for the reaction of glycerol and urea with 75% glycerol conversion and 98% selectivity to GC. Such excellent activity of the catalyst is explained based on the presence of both basic and acidic sites on the same catalyst which activates the glycerol and urea molecules, respectively.

Solvent-mediated molar conductivity of protic ionic liquids - Thawarkar, Sachin; Khupse, Nageshwar D.; Kumar, Anil (Physical Chemistry Chemical Physics, 2015)
The molar conductivity, A(m), of protic ionic liquids (PILs) in molecular solvents is measured at 298.15 K. The decrease in the A(m) values of PILs is observed with an increase in the concentration of PILs. The limiting molar conductivities, A(m)(0), were obtained for each PIL in different molecular solvents using a least squares method. The A(m)(0) data for PILs were correlated with the structural aspects of PILs and solvent properties. The polar protic solvents show poor ionic association as compared to the polar aprotic solvents, which is discussed on the basis of the hydrogen bond donating (HBD) ability of solvents and PILs. The alkyl chain substitution of anions plays a significant role in the ionic association of the PILs. The diffusion coefficient D-0 and the transport number t were determined, which were consistent with the A(m)(0) values of PILs in water. The A(m)(0) and D-0 values are dependent on the hydrodynamic radius of anions of these ionic liquids. The extent of ionic association for each PIL was discussed using temperature dependent A(m) data for aqueous PIL systems in terms of the Walden plot.

Sophorolipid assisted tunable and rapid gelation of silk fibroin to form porous biomedical scaffolds - Dubey, Parul; Nawale, Laxman; Sarkar, Dhiman; Nisal, Anuya; Prabhune, Asmita (RSC Advances, 2015)
Three dimensional polymer hydrogels, based on both natural and synthetic polymers, are increasingly being used as scaffolds and drug delivery vehicles for biomedical applications. Fibrous protein, silk fibroin (SF), obtained from the Bombyx mori silkworm is a promising candidate in this area. However, SF has a long gelation time of about a few weeks that can only be reduced by non-physiological treatments (e. g. high temperature, ultrasonication and low pH) or by addition of a chemical and non-biodegradable polymer and/or surfactant. We report here accelerated gelation of SF under physiological conditions using a biosurfactant, sophorolipid (SL) as a gelling agent. SL and SF are completely miscible and form a very clear solution upon mixing. Hence it is interesting to see that this clear solution gels in a time span of just a few hours. The hydrogels so formed have pore architecture, porosities and mechanical stability ideally suited for tissue culture applications. Here we also demonstrate that mouse fibroblast cells not only adhere to but also extensively proliferate on these SF-SL scaffolds.

Specific reagent for Cr(III): imaging cellular uptake of Cr(III) in Hct116 cells and theoretical rationalization - Ali, Firoj; Saha, Sukdeb; Maity, Arunava; Taye, Nandaraj; Si, Mrinal Kanti; Suresh, E.; Ganguly, Bishwajit; Chattopadhyay, Samit; Das, Amitava (Journal of Physical Chemistry B, 2015)
A new rhodamine-based reagent (L-1), trapped inside the micellar structure of biologically benign Triton-X 100, could be used for specific recognition of Cr(III) in aqueous buffer medium having physiological pH. This visible light excitable reagent on selective binding to Cr(III) resulted in a strong fluorescence turn-on response with a maximum at similar to 583 nm and tail of that luminescence band extended until 650 nm, an optical response that is desired for avoiding the cellular autofluorescence. Interference studies confirm that other metal ions do not interfere with the detection process of Cr(III) in aqueous buffer medium having pH 7.2. To examine the nature of binding of Cr(III) to L-1, various spectroscopic studies are performed with the model reagent L-1 which tend to support Cr(III)-eta(2)-olefin pi-interactions involving two olefin bonds in molecular probe L-1. Computational studies are also performed with another model reagent L-M to examine the possibility of such Cr(III)-eta(2)-olefin pi-interactions. Presumably, polar functional groups of the model reagent L-M upon coordination to the Cr(III) center effectively reduce the formal charge on the metal ion and this is further substantiated by results of the theoretical studies. This assembly is found to be cell membrane permeable and shows insignificant toxicity toward live colon cancer cells (Hct116). Confocal laser scanning microscopic studies further revealed that the reagent L-1 could be used as an imaging reagent for detection of cellular uptake of Cr(III) in pure aqueous buffer medium by Hct116 cells. Examples of a specific reagent for paramagnetic Cr(III) with luminescence ON response are scanty in the contemporary literature. This ligand design helped us in achieving the turn on response by utilizing the conversion from spirolactam to an acyclic xanthene form on coordination to Cr(III).

Spectral analysis of the emission current noise exhibited by few layer WS2 nanosheets emitter - Suryawanshi, Sachin R.; Kolhe, Pankaj S.; Rout, Chandra S.; Late, Dattatray J.; More, Mahendra A. (Ultramicroscopy, 2015)
Spectral analysis of the field emission (FE) current fluctuations has been carried out at the base pressure similar to 1 x 10(-8) mbar. The emission current stability investigated at preset value of 2 mu A is characterized by `step like fluctuation. The spectral analysis performed on a FFT (Fast Fourier Transform) analyzer revealed that the observed noise is of 1/f(alpha) type, with the value of alpha as similar to 1.05. The estimated value of alpha implies that the current fluctuations are mainly due the various processes occurring on atomic scale like adsorption, migration, and/or desorption of the residual gas species on the emitter surface. (C) 2014 Elsevier B.V. All rights reserved.
Keywords: Current fluctuations; field emission; Noise; WS2 nanosheets

Spectroscopic and ab initio investigation of 2,6-difluorophenylacetylene-amine complexes: coexistence of C-H center dot center dot center dot N and lone-pair center dot center dot center dot pi complexes and intermolecular coulombic decay - Mondal, Sohidul Islam; Dey, Arghya; Sen, Saumik; Patwari, G. Naresh; Ghosh, Debashree (Physical Chemistry Chemical Physics, 2015)
Binary complexes of 2,6-difluorophenylacetylene with methylamine, dimethylamine, trimethylamine and triethylamine were investigated using one colour resonant two photon ionization and infrared-optical double resonance spectroscopic techniques combined with high level ab initio calculations. All four amines form C-Ac-H center dot center dot center dot N hydrogen-bonded complexes. Additionally trimethylamine and triethylamine form complexes characterized by Lp center dot center dot center dot pi interactions, due to the electron deficient nature of the phenyl ring of 2,6-difluorophenylacetylene. The Lp center dot center dot center dot pi interacting structure of the 2,6-difluorophenylacetylenetrimethylamine complex is about 1.5 kJ mol(-1) higher in energy than the C-Ac-H center dot center dot center dot N hydrogen-bonded structure, which is the global minimum. Energy decomposition analysis indicates that the electrostatics and dispersion interactions favour the formation of C-Ac-H center dot center dot center dot N and Lp center dot center dot center dot pi complexes, respectively. Interestingly the C-Ac-H center dot center dot center dot N hydrogen-bonded complex of 2,6-difluorophenylacetylene-triethylamine showed a smaller shift in the acetylenic C-H stretching frequency than the 2,6-difluorophenylacetylene-trimethylamine complex. The observed fragmentation of the binary complexes of 2,6-difluorophenylacetylene with the four amines following resonant two-photon ionization can be explained on the basis of the intermolecular coulombic decay process.